diff --git a/.eslintrc.js b/.eslintrc.js
index 95a83a49ef9f..72e1ccbc42b1 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -210,7 +210,8 @@ module.exports = {
       files: [
         "dom/push/test/mockpushserviceparent.js",
         "browser/components/extensions/**",
-        "toolkit/**",
+        "toolkit/components/extensions/**",
+        "toolkit/mozapps/extensions/**",
       ],
       rules: {
         "mozilla/no-cu-reportError": "off",
diff --git a/toolkit/actors/AutoCompleteChild.jsm b/toolkit/actors/AutoCompleteChild.jsm
index de3023b6a90c..3c0ea952987a 100644
--- a/toolkit/actors/AutoCompleteChild.jsm
+++ b/toolkit/actors/AutoCompleteChild.jsm
@@ -84,7 +84,7 @@ class AutoCompleteChild extends JSWindowActorChild {
       try {
         listener.popupStateChanged(messageName, data, this.contentWindow);
       } catch (ex) {
-        Cu.reportError(ex);
+        console.error(ex);
       }
     }
   }
diff --git a/toolkit/actors/AutoCompleteParent.jsm b/toolkit/actors/AutoCompleteParent.jsm
index 910f74719fcd..577cc3cd3571 100644
--- a/toolkit/actors/AutoCompleteParent.jsm
+++ b/toolkit/actors/AutoCompleteParent.jsm
@@ -488,7 +488,7 @@ class AutoCompleteParent extends JSWindowActorParent {
       try {
         listener(window);
       } catch (ex) {
-        Cu.reportError(ex);
+        console.error(ex);
       }
     }
   }
diff --git a/toolkit/actors/PrintingChild.jsm b/toolkit/actors/PrintingChild.jsm
index f85a8303ade7..93b7d7787e85 100644
--- a/toolkit/actors/PrintingChild.jsm
+++ b/toolkit/actors/PrintingChild.jsm
@@ -93,7 +93,7 @@ class PrintingChild extends JSWindowActorChild {
     try {
       article = await lazy.ReaderMode.parseDocument(contentWindow.document);
     } catch (ex) {
-      Cu.reportError(ex);
+      console.error(ex);
     }
 
     await new Promise(resolve => {
diff --git a/toolkit/actors/RemotePageChild.jsm b/toolkit/actors/RemotePageChild.jsm
index cd4fbaad2751..dfbc1b62ebd3 100644
--- a/toolkit/actors/RemotePageChild.jsm
+++ b/toolkit/actors/RemotePageChild.jsm
@@ -109,7 +109,7 @@ class RemotePageChild extends JSWindowActorChild {
       try {
         listener(clonedMessage);
       } catch (e) {
-        Cu.reportError(e);
+        console.error(e);
       }
     }
   }
diff --git a/toolkit/actors/UAWidgetsChild.jsm b/toolkit/actors/UAWidgetsChild.jsm
index a015e2456b26..ec6cc2d8a8be 100644
--- a/toolkit/actors/UAWidgetsChild.jsm
+++ b/toolkit/actors/UAWidgetsChild.jsm
@@ -56,7 +56,7 @@ class UAWidgetsChild extends JSWindowActorChild {
         this.unwrap(aElement.openOrClosedShadowRoot) !=
         this.unwrap(widget.shadowRoot)
       ) {
-        Cu.reportError(
+        console.error(
           "Getting a UAWidgetSetupOrChange event without the ShadowRoot. " +
             "Torn down already?"
         );
@@ -65,7 +65,7 @@ class UAWidgetsChild extends JSWindowActorChild {
       try {
         widget.onchange();
       } catch (ex) {
-        Cu.reportError(ex);
+        console.error(ex);
       }
     }
   }
@@ -109,7 +109,7 @@ class UAWidgetsChild extends JSWindowActorChild {
     }
 
     if (!uri || !widgetName) {
-      Cu.reportError(
+      console.error(
         "Getting a UAWidgetSetupOrChange event on undefined element."
       );
       return;
@@ -117,7 +117,7 @@ class UAWidgetsChild extends JSWindowActorChild {
 
     let shadowRoot = aElement.openOrClosedShadowRoot;
     if (!shadowRoot) {
-      Cu.reportError(
+      console.error(
         "Getting a UAWidgetSetupOrChange event without the Shadow Root. " +
           "Torn down already?"
       );
@@ -143,13 +143,13 @@ class UAWidgetsChild extends JSWindowActorChild {
       widget = widget.wrappedJSObject;
     }
     if (this.unwrap(widget.shadowRoot) != this.unwrap(shadowRoot)) {
-      Cu.reportError("Widgets should expose their shadow root.");
+      console.error("Widgets should expose their shadow root.");
     }
     this.widgets.set(aElement, { widget, widgetName });
     try {
       widget.onsetup();
     } catch (ex) {
-      Cu.reportError(ex);
+      console.error(ex);
     }
   }
 
@@ -162,7 +162,7 @@ class UAWidgetsChild extends JSWindowActorChild {
       try {
         widget.teardown();
       } catch (ex) {
-        Cu.reportError(ex);
+        console.error(ex);
       }
     }
     this.widgets.delete(aElement);
@@ -228,7 +228,7 @@ class UAWidgetsChild extends JSWindowActorChild {
             try {
               widget.onPrefChange(prefKey, newValue);
             } catch (ex) {
-              Cu.reportError(ex);
+              console.error(ex);
             }
           }
         }
diff --git a/toolkit/actors/WebChannelChild.sys.mjs b/toolkit/actors/WebChannelChild.sys.mjs
index 62ff0e945f94..563f2566a0df 100644
--- a/toolkit/actors/WebChannelChild.sys.mjs
+++ b/toolkit/actors/WebChannelChild.sys.mjs
@@ -65,7 +65,7 @@ export class WebChannelChild extends JSWindowActorChild {
           whitelisted => principal.originNoSuffix == whitelisted.originNoSuffix
         );
         if (!objectsAllowed) {
-          Cu.reportError(
+          console.error(
             "WebChannelMessageToChrome sent with an object from a non-whitelisted principal"
           );
           return;
@@ -82,7 +82,7 @@ export class WebChannelChild extends JSWindowActorChild {
         principal,
       });
     } else {
-      Cu.reportError("WebChannel message failed. No message detail.");
+      console.error("WebChannel message failed. No message detail.");
     }
   }
 
@@ -99,7 +99,7 @@ export class WebChannelChild extends JSWindowActorChild {
         eventTarget = ContentDOMReference.resolve(eventTarget);
       }
       if (!eventTarget) {
-        Cu.reportError("WebChannel message failed. No target.");
+        console.error("WebChannel message failed. No target.");
         return;
       }
 
@@ -123,10 +123,10 @@ export class WebChannelChild extends JSWindowActorChild {
           })
         );
       } else {
-        Cu.reportError("WebChannel message failed. Principal mismatch.");
+        console.error("WebChannel message failed. Principal mismatch.");
       }
     } else {
-      Cu.reportError("WebChannel message failed. No message data.");
+      console.error("WebChannel message failed. No message data.");
     }
   }
 }
diff --git a/toolkit/actors/WebChannelParent.sys.mjs b/toolkit/actors/WebChannelParent.sys.mjs
index 872ad5dde36a..98b3ad093a31 100644
--- a/toolkit/actors/WebChannelParent.sys.mjs
+++ b/toolkit/actors/WebChannelParent.sys.mjs
@@ -22,7 +22,7 @@ export class WebChannelParent extends JSWindowActorParent {
       try {
         data = JSON.parse(data);
       } catch (e) {
-        Cu.reportError("Failed to parse WebChannel data as a JSON object");
+        console.error("Failed to parse WebChannel data as a JSON object");
         return;
       }
     }
@@ -52,7 +52,7 @@ export class WebChannelParent extends JSWindowActorParent {
         }
       }
     } else {
-      Cu.reportError("WebChannel channel id missing");
+      console.error("WebChannel channel id missing");
     }
   }
 
@@ -85,8 +85,8 @@ export class WebChannelParent extends JSWindowActorParent {
           principal,
         });
     } else {
-      Cu.reportError("Failed to send a WebChannel error. Target invalid.");
+      console.error("Failed to send a WebChannel error. Target invalid.");
     }
-    Cu.reportError(id.toString() + " error message. " + errorMsg);
+    console.error(id.toString() + " error message. ", errorMsg);
   }
 }
diff --git a/toolkit/components/DefaultCLH.jsm b/toolkit/components/DefaultCLH.jsm
index d4b104b1b960..69e62b381245 100644
--- a/toolkit/components/DefaultCLH.jsm
+++ b/toolkit/components/DefaultCLH.jsm
@@ -45,7 +45,7 @@ nsDefaultCLH.prototype = {
       }
 
       dump(out + "\n");
-      Cu.reportError(out);
+      console.error(out);
     }
 
     var printDirList;
@@ -65,7 +65,7 @@ nsDefaultCLH.prototype = {
       }
 
       dump(out + "\n");
-      Cu.reportError(out);
+      console.error(out);
     }
 
     if (cmdLine.handleFlag("silent", false)) {
diff --git a/toolkit/components/aboutthirdparty/content/aboutThirdParty.js b/toolkit/components/aboutthirdparty/content/aboutThirdParty.js
index eb166edf6887..08e50a2fff27 100644
--- a/toolkit/components/aboutthirdparty/content/aboutThirdParty.js
+++ b/toolkit/components/aboutthirdparty/content/aboutThirdParty.js
@@ -65,7 +65,7 @@ async function fetchData() {
       !(e instanceof Components.Exception) ||
       e.result != Cr.NS_ERROR_NOT_AVAILABLE
     ) {
-      Cu.reportError(e);
+      console.error(e);
     }
   }
 
@@ -231,7 +231,7 @@ async function onBlock(event) {
     event.target.setAttribute("data-l10n-id", blockButtonL10nId);
     updatedBlocklist = true;
   } catch (ex) {
-    Cu.reportError("Failed to update the blocklist file - " + ex.result);
+    console.error("Failed to update the blocklist file - ", ex.result);
   } finally {
     processingBlockRequest = false;
   }
@@ -582,7 +582,7 @@ async function collectCrashInfo() {
     try {
       return BigInt(maybeBigInt);
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
     }
     return NaN;
   };
@@ -626,7 +626,7 @@ async function onLoad() {
       e.target.disabled = true;
 
       const data = await fetchData();
-      await copyDataToClipboard(data || []).catch(Cu.reportError);
+      await copyDataToClipboard(data || []).catch(console.error);
 
       e.target.disabled = false;
     });
@@ -665,7 +665,7 @@ async function onLoad() {
       // we show the reload button to call visualizeData again.
       button.hidden = false;
     })
-    .catch(Cu.reportError);
+    .catch(console.error);
 
   const data = await fetchData();
   // Used for testing purposes
@@ -688,5 +688,5 @@ try {
 } catch (ex) {
   // Do nothing if we fail to create a singleton instance,
   // showing the default no-module message.
-  Cu.reportError(ex);
+  console.error(ex);
 }
diff --git a/toolkit/components/aboutwindowsmessages/content/aboutWindowsMessages.js b/toolkit/components/aboutwindowsmessages/content/aboutWindowsMessages.js
index 4aef3d0dd73c..0896ae766926 100644
--- a/toolkit/components/aboutwindowsmessages/content/aboutWindowsMessages.js
+++ b/toolkit/components/aboutwindowsmessages/content/aboutWindowsMessages.js
@@ -66,5 +66,5 @@ try {
 } catch (ex) {
   // Do nothing if we fail to create a singleton instance,
   // showing the default no-module message.
-  Cu.reportError(ex);
+  console.error(ex);
 }
diff --git a/toolkit/components/antitracking/PartitioningExceptionListService.jsm b/toolkit/components/antitracking/PartitioningExceptionListService.jsm
index 99e88e810e7f..b024524ba6d3 100644
--- a/toolkit/components/antitracking/PartitioningExceptionListService.jsm
+++ b/toolkit/components/antitracking/PartitioningExceptionListService.jsm
@@ -40,7 +40,7 @@ class Feature {
 
   observe(subject, topic, data) {
     if (topic != "nsPref:changed" || data != this.prefName) {
-      Cu.reportError(`Unexpected event ${topic} with ${data}`);
+      console.error(`Unexpected event ${topic} with ${data}`);
       return;
     }
 
diff --git a/toolkit/components/antitracking/TrackingDBService.jsm b/toolkit/components/antitracking/TrackingDBService.jsm
index 320791ee3704..ff2fa5fb267c 100644
--- a/toolkit/components/antitracking/TrackingDBService.jsm
+++ b/toolkit/components/antitracking/TrackingDBService.jsm
@@ -290,7 +290,7 @@ TrackingDBService.prototype = {
         }
       });
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
     }
 
     // If milestone CFR messaging is not enabled we don't need to update the milestone pref or send the event.
diff --git a/toolkit/components/antitracking/URLQueryStrippingListService.jsm b/toolkit/components/antitracking/URLQueryStrippingListService.jsm
index c8682f3121f0..108900caba31 100644
--- a/toolkit/components/antitracking/URLQueryStrippingListService.jsm
+++ b/toolkit/components/antitracking/URLQueryStrippingListService.jsm
@@ -130,7 +130,7 @@ class URLQueryStrippingListService {
         break;
 
       default:
-        Cu.reportError(`Unexpected pref name ${pref}`);
+        console.error(`Unexpected pref name ${pref}`);
         return;
     }
 
@@ -224,7 +224,7 @@ class URLQueryStrippingListService {
         this._onPrefUpdate(data, prefValue);
         break;
       default:
-        Cu.reportError(`Unexpected event ${topic}`);
+        console.error(`Unexpected event ${topic}`);
     }
   }
 
diff --git a/toolkit/components/cleardata/ClearDataService.sys.mjs b/toolkit/components/cleardata/ClearDataService.sys.mjs
index b77687268ae2..5f0e535f4811 100644
--- a/toolkit/components/cleardata/ClearDataService.sys.mjs
+++ b/toolkit/components/cleardata/ClearDataService.sys.mjs
@@ -872,7 +872,7 @@ const StorageAccessCleaner = {
         try {
           Services.perms.removePermission(perm);
         } catch (ex) {
-          Cu.reportError(ex);
+          console.error(ex);
         }
       });
   },
@@ -1174,7 +1174,7 @@ const ClientAuthRememberCleaner = {
               originSuffix
             );
           } catch (e) {
-            Cu.reportError(e);
+            console.error(e);
           }
         }
 
@@ -1572,7 +1572,7 @@ ClearDataService.prototype = Object.freeze({
     // This is mainly needed for GeckoView that doesn't start QMS on startup
     // time.
     if (!Services.qms) {
-      Cu.reportError("Failed initializiation of QuotaManagerService.");
+      console.error("Failed initializiation of QuotaManagerService.");
     }
   },
 
@@ -1733,7 +1733,7 @@ ClearDataService.prototype = Object.freeze({
       return Promise.all(
         c.cleaners.map(cleaner => {
           return aHelper(cleaner).catch(e => {
-            Cu.reportError(e);
+            console.error(e);
             resultFlags |= c.flag;
           });
         })
diff --git a/toolkit/components/cleardata/PrincipalsCollector.sys.mjs b/toolkit/components/cleardata/PrincipalsCollector.sys.mjs
index 6315c57ad73c..b3c82880ba73 100644
--- a/toolkit/components/cleardata/PrincipalsCollector.sys.mjs
+++ b/toolkit/components/cleardata/PrincipalsCollector.sys.mjs
@@ -112,7 +112,7 @@ export class PrincipalsCollector {
         resolve(principalsMap);
       };
     }).catch(ex => {
-      Cu.reportError("QuotaManagerService promise failed: " + ex);
+      console.error("QuotaManagerService promise failed: ", ex);
       return [];
     });
 
diff --git a/toolkit/components/contentprefs/ContentPrefService2.jsm b/toolkit/components/contentprefs/ContentPrefService2.jsm
index 753ebeca4bb4..8091261a46e9 100644
--- a/toolkit/components/contentprefs/ContentPrefService2.jsm
+++ b/toolkit/components/contentprefs/ContentPrefService2.jsm
@@ -914,10 +914,10 @@ ContentPrefService2.prototype = {
         try {
           callbacks.onError(e);
         } catch (e) {
-          Cu.reportError(e);
+          console.error(e);
         }
       } else {
-        Cu.reportError(e);
+        console.error(e);
       }
     }
 
@@ -926,7 +926,7 @@ ContentPrefService2.prototype = {
         try {
           callbacks.onRow(row);
         } catch (e) {
-          Cu.reportError(e);
+          console.error(e);
         }
       }
     }
@@ -940,7 +940,7 @@ ContentPrefService2.prototype = {
         rows && !!rows.length
       );
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
     }
   },
 
@@ -1034,7 +1034,7 @@ ContentPrefService2.prototype = {
       try {
         observer.onContentPrefRemoved(aGroup, aName, aIsPrivate);
       } catch (ex) {
-        Cu.reportError(ex);
+        console.error(ex);
       }
     }
   },
@@ -1052,7 +1052,7 @@ ContentPrefService2.prototype = {
       try {
         observer.onContentPrefSet(aGroup, aName, aValue, aIsPrivate);
       } catch (ex) {
-        Cu.reportError(ex);
+        console.error(ex);
       }
     }
   },
@@ -1184,7 +1184,7 @@ ContentPrefService2.prototype = {
       try {
         await this._failover(conn, path);
       } catch (e) {
-        Cu.reportError(e);
+        console.error(e);
         throw e;
       }
       return this._getConnection(++aAttemptNum);
@@ -1207,14 +1207,14 @@ ContentPrefService2.prototype = {
         return null;
       }
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
       return resetAndRetry(e);
     }
 
     try {
       await this._dbMaybeInit(conn);
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
       return resetAndRetry(e);
     }
 
diff --git a/toolkit/components/contentprefs/ContentPrefUtils.jsm b/toolkit/components/contentprefs/ContentPrefUtils.jsm
index aed82ddf41f8..9fc5c0a77fbd 100644
--- a/toolkit/components/contentprefs/ContentPrefUtils.jsm
+++ b/toolkit/components/contentprefs/ContentPrefUtils.jsm
@@ -43,7 +43,7 @@ function safeCallback(callbackObj, methodName, args) {
   try {
     callbackObj[methodName].apply(callbackObj, args);
   } catch (err) {
-    Cu.reportError(err);
+    console.error(err);
   }
 }
 
diff --git a/toolkit/components/contextualidentity/ContextualIdentityService.sys.mjs b/toolkit/components/contextualidentity/ContextualIdentityService.sys.mjs
index d31cf05c8c21..f35ca9c2206e 100644
--- a/toolkit/components/contextualidentity/ContextualIdentityService.sys.mjs
+++ b/toolkit/components/contextualidentity/ContextualIdentityService.sys.mjs
@@ -205,7 +205,7 @@ _ContextualIdentityService.prototype = {
   loadError(error) {
     if (error != null && error.name != "NotFoundError") {
       // Let's report the error.
-      Cu.reportError(error);
+      console.error(error);
     }
 
     // If synchronous loading happened in the meantime, exit now.
diff --git a/toolkit/components/cookiebanners/CookieBannerParent.jsm b/toolkit/components/cookiebanners/CookieBannerParent.jsm
index be12dcbdf0c0..066f17dc35d4 100644
--- a/toolkit/components/cookiebanners/CookieBannerParent.jsm
+++ b/toolkit/components/cookiebanners/CookieBannerParent.jsm
@@ -132,9 +132,9 @@ class CookieBannerParent extends JSWindowActorParent {
         // is disabled. We will fallback to global pref setting if any errors
         // occur.
         if (e.result == Cr.NS_ERROR_NOT_AVAILABLE) {
-          Cu.reportError("The cookie banner handling service is not available");
+          console.error("The cookie banner handling service is not available");
         } else {
-          Cu.reportError("Fail on getting domain pref:" + e);
+          console.error("Fail on getting domain pref:", e);
         }
       }
     }
diff --git a/toolkit/components/crashes/CrashManager.in.jsm b/toolkit/components/crashes/CrashManager.in.jsm
index b5006f43b0e2..402a269e2a5c 100644
--- a/toolkit/components/crashes/CrashManager.in.jsm
+++ b/toolkit/components/crashes/CrashManager.in.jsm
@@ -83,7 +83,7 @@ function parseAndRemoveField(obj, field) {
     try {
       value = JSON.parse(obj[field]);
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
     }
 
     delete obj[field];
@@ -344,10 +344,10 @@ CrashManager.prototype = Object.freeze({
                 break;
 
               default:
-                Cu.reportError(
+                console.error(
                   "Unhandled crash event file return code. Please " +
-                    "file a bug: " +
-                    result
+                    "file a bug: ",
+                  result
                 );
             }
           } catch (ex) {
@@ -360,7 +360,7 @@ CrashManager.prototype = Object.freeze({
               //
               // If we get here, report the error and delete the source file
               // so we don't see it again.
-              Cu.reportError(
+              console.error(
                 "Exception when processing crash event file: " +
                   lazy.Log.exceptionStr(ex)
               );
@@ -450,10 +450,10 @@ CrashManager.prototype = Object.freeze({
   addCrash(processType, crashType, id, date, metadata) {
     let promise = (async () => {
       if (!this.isValidProcessType(processType)) {
-        Cu.reportError(
-          "Unhandled process type. Please file a bug: '" +
-            processType +
-            "'. Ignore in the context of " +
+        console.error(
+          "Unhandled process type. Please file a bug: '",
+          processType,
+          "'. Ignore in the context of " +
             "test_crash_manager.js:test_addCrashWrong()."
         );
         return;
@@ -645,7 +645,7 @@ CrashManager.prototype = Object.freeze({
 
         return entries;
       } catch (e) {
-        Cu.reportError(e);
+        console.error(e);
         return [];
       }
     })();
diff --git a/toolkit/components/crashes/CrashService.jsm b/toolkit/components/crashes/CrashService.jsm
index b3719fd526e7..6e79c348b969 100644
--- a/toolkit/components/crashes/CrashService.jsm
+++ b/toolkit/components/crashes/CrashService.jsm
@@ -31,7 +31,7 @@ async function maybeRunMinidumpAnalyzer(minidumpPath, allThreads) {
   }
 
   await runMinidumpAnalyzer(minidumpPath, allThreads).catch(e =>
-    Cu.reportError(e)
+    console.error(e)
   );
 }
 
@@ -123,7 +123,7 @@ function computeMinidumpHash(minidumpPath) {
 
       return hash;
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
       return null;
     }
   })();
@@ -146,7 +146,7 @@ function processExtraFile(extraPath) {
 
       return JSON.parse(decoder.decode(extraData));
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
       return {};
     }
   })();
diff --git a/toolkit/components/crashmonitor/CrashMonitor.jsm b/toolkit/components/crashmonitor/CrashMonitor.jsm
index fd3bc49fd2c8..6a19150b2125 100644
--- a/toolkit/components/crashmonitor/CrashMonitor.jsm
+++ b/toolkit/components/crashmonitor/CrashMonitor.jsm
@@ -108,7 +108,7 @@ var CrashMonitorInternal = {
       } catch (ex) {
         // Ignore file not found errors, but report all others.
         if (ex.name !== "NotFoundError") {
-          Cu.reportError(
+          console.error(
             `Error while loading crash monitor data: ${ex.message}`
           );
         }
@@ -117,7 +117,7 @@ var CrashMonitorInternal = {
 
       // If `notifications` isn't an object, then the monitor data isn't valid.
       if (Object(notifications) !== notifications) {
-        Cu.reportError(
+        console.error(
           "Error while parsing crash monitor data: invalid monitor data"
         );
         return null;
diff --git a/toolkit/components/downloads/DownloadCore.sys.mjs b/toolkit/components/downloads/DownloadCore.sys.mjs
index 2fb210fcb3ae..cd42bec36ed6 100644
--- a/toolkit/components/downloads/DownloadCore.sys.mjs
+++ b/toolkit/components/downloads/DownloadCore.sys.mjs
@@ -596,7 +596,7 @@ Download.prototype = {
     this._deferSucceeded.resolve();
 
     if (this.launchWhenSucceeded) {
-      this.launch().catch(Cu.reportError);
+      this.launch().catch(console.error);
 
       // Always schedule files to be deleted at the end of the private browsing
       // mode, regardless of the value of the pref.
@@ -1072,7 +1072,7 @@ Download.prototype = {
 
         this._notifyChange();
       }
-    })().catch(Cu.reportError);
+    })().catch(console.error);
   },
 
   /**
@@ -2053,7 +2053,7 @@ DownloadSaver.prototype = {
   addToHistory() {
     if (AppConstants.MOZ_PLACES) {
       lazy.DownloadHistory.addDownloadToHistory(this.download).catch(
-        Cu.reportError
+        console.error
       );
     }
   },
diff --git a/toolkit/components/downloads/DownloadHistory.sys.mjs b/toolkit/components/downloads/DownloadHistory.sys.mjs
index 5fcc12d3befd..9efac0bebf8b 100644
--- a/toolkit/components/downloads/DownloadHistory.sys.mjs
+++ b/toolkit/components/downloads/DownloadHistory.sys.mjs
@@ -573,7 +573,7 @@ var DownloadHistoryList = function(publicList, place) {
   this._slotForDownload = new WeakMap();
 
   // Start the asynchronous queries to retrieve history and session downloads.
-  publicList.addView(this).catch(Cu.reportError);
+  publicList.addView(this).catch(console.error);
   let query = {},
     options = {};
   lazy.PlacesUtils.history.queryStringToQuery(place, query, options);
diff --git a/toolkit/components/downloads/DownloadIntegration.sys.mjs b/toolkit/components/downloads/DownloadIntegration.sys.mjs
index 325e9b4d3449..273db66dc410 100644
--- a/toolkit/components/downloads/DownloadIntegration.sys.mjs
+++ b/toolkit/components/downloads/DownloadIntegration.sys.mjs
@@ -1017,7 +1017,7 @@ var DownloadObserver = {
     };
 
     // We register the view asynchronously.
-    aList.addView(downloadsView).catch(Cu.reportError);
+    aList.addView(downloadsView).catch(console.error);
   },
 
   /**
@@ -1105,8 +1105,8 @@ var DownloadObserver = {
 
           // We can remove the downloads and finalize them in parallel.
           for (let download of downloads) {
-            list.remove(download).catch(Cu.reportError);
-            download.finalize(true).catch(Cu.reportError);
+            list.remove(download).catch(console.error);
+            download.finalize(true).catch(console.error);
           }
         })();
         // Handle test mode
diff --git a/toolkit/components/downloads/DownloadLegacy.sys.mjs b/toolkit/components/downloads/DownloadLegacy.sys.mjs
index 31018441dcc9..ae38b0d26cf8 100644
--- a/toolkit/components/downloads/DownloadLegacy.sys.mjs
+++ b/toolkit/components/downloads/DownloadLegacy.sys.mjs
@@ -119,7 +119,7 @@ DownloadLegacyTransfer.prototype = {
             }
           });
         })
-        .catch(Cu.reportError);
+        .catch(console.error);
     } else if (
       aStateFlags & Ci.nsIWebProgressListener.STATE_STOP &&
       aStateFlags & Ci.nsIWebProgressListener.STATE_IS_NETWORK
@@ -137,7 +137,7 @@ DownloadLegacyTransfer.prototype = {
           }
           download.saver.onTransferFinished(aStatus);
         })
-        .catch(Cu.reportError);
+        .catch(console.error);
 
       // Release the reference to the component executing the download.
       this._cancelable = null;
@@ -183,7 +183,7 @@ DownloadLegacyTransfer.prototype = {
         .then(download => {
           download.saver.onTransferFinished(aStatus);
         })
-        .catch(Cu.reportError);
+        .catch(console.error);
     }
   },
 
@@ -236,7 +236,7 @@ DownloadLegacyTransfer.prototype = {
           this._delayedMaxTotalProgress
         );
       })
-      .catch(Cu.reportError);
+      .catch(console.error);
   },
   _hasDelayedProgress: false,
   _delayedCurTotalProgress: 0,
@@ -447,7 +447,7 @@ DownloadLegacyTransfer.prototype = {
           aDownload._notifyChange();
         }
       })
-      .catch(Cu.reportError);
+      .catch(console.error);
   },
 
   setSha256Hash(hash) {
diff --git a/toolkit/components/downloads/DownloadList.sys.mjs b/toolkit/components/downloads/DownloadList.sys.mjs
index 3df6a45b443a..101a3ab2b94e 100644
--- a/toolkit/components/downloads/DownloadList.sys.mjs
+++ b/toolkit/components/downloads/DownloadList.sys.mjs
@@ -357,10 +357,10 @@ DownloadList.prototype = {
           // don't need to wait for the procedure to be complete before
           // processing the other downloads in the list.
           let removePartialData = !sameFileIsDownloading;
-          download.finalize(removePartialData).catch(Cu.reportError);
+          download.finalize(removePartialData).catch(console.error);
         }
       }
-    })().catch(Cu.reportError);
+    })().catch(console.error);
   },
 };
 
@@ -380,8 +380,8 @@ export var DownloadCombinedList = function(aPublicList, aPrivateList) {
   DownloadList.call(this);
   this._publicList = aPublicList;
   this._privateList = aPrivateList;
-  aPublicList.addView(this).catch(Cu.reportError);
-  aPrivateList.addView(this).catch(Cu.reportError);
+  aPublicList.addView(this).catch(console.error);
+  aPrivateList.addView(this).catch(console.error);
 };
 
 DownloadCombinedList.prototype = {
diff --git a/toolkit/components/downloads/test/unit/head.js b/toolkit/components/downloads/test/unit/head.js
index e2e251dbc0ac..e5293304cd02 100644
--- a/toolkit/components/downloads/test/unit/head.js
+++ b/toolkit/components/downloads/test/unit/head.js
@@ -903,7 +903,7 @@ function registerInterruptibleHandler(aPath, aFirstPartFn, aSecondPartFn) {
         aResponse.finish();
         info("Interruptible request finished.");
       })
-      .catch(Cu.reportError);
+      .catch(console.error);
   });
 }
 
diff --git a/toolkit/components/featuregates/FeatureGateImplementation.jsm b/toolkit/components/featuregates/FeatureGateImplementation.jsm
index 6878d3372df2..09a5b98704e7 100644
--- a/toolkit/components/featuregates/FeatureGateImplementation.jsm
+++ b/toolkit/components/featuregates/FeatureGateImplementation.jsm
@@ -268,7 +268,7 @@ class FeatureGateImplementation {
       try {
         observer[method](...args);
       } catch (err) {
-        Cu.reportError(err);
+        console.error(err);
       }
     }
   }
@@ -292,7 +292,7 @@ class FeatureGateImplementation {
         }
       }
     } else {
-      Cu.reportError(
+      console.error(
         new Error(`Unexpected event observed: ${aSubject}, ${aTopic}, ${aData}`)
       );
     }
diff --git a/toolkit/components/formautofill/.eslintrc.js b/toolkit/components/formautofill/.eslintrc.js
index 64779b1fcdeb..12bf577565d3 100644
--- a/toolkit/components/formautofill/.eslintrc.js
+++ b/toolkit/components/formautofill/.eslintrc.js
@@ -39,7 +39,7 @@ module.exports = {
     "max-nested-callbacks": ["error", 4],
 
     // Disallow using the console API.
-    "no-console": "error",
+    "no-console": ["error", { allow: ["error"] }],
 
     // Disallow fallthrough of case statements, except if there is a comment.
     "no-fallthrough": "error",
diff --git a/toolkit/components/formautofill/FormAutofillParent.jsm b/toolkit/components/formautofill/FormAutofillParent.jsm
index 418e1f83f9d1..a1f60fc66266 100644
--- a/toolkit/components/formautofill/FormAutofillParent.jsm
+++ b/toolkit/components/formautofill/FormAutofillParent.jsm
@@ -401,7 +401,7 @@ class FormAutofillParent extends JSWindowActorParent {
           );
         }
       } catch (ex) {
-        Cu.reportError(ex);
+        console.error(ex);
       }
     }
   }
diff --git a/toolkit/components/messaging-system/lib/SpecialMessageActions.jsm b/toolkit/components/messaging-system/lib/SpecialMessageActions.jsm
index 81eec6822f2b..4dae5153b9b6 100644
--- a/toolkit/components/messaging-system/lib/SpecialMessageActions.jsm
+++ b/toolkit/components/messaging-system/lib/SpecialMessageActions.jsm
@@ -81,7 +81,7 @@ const SpecialMessageActions = {
         install
       );
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
     }
   },
 
diff --git a/toolkit/components/messaging-system/targeting/Targeting.jsm b/toolkit/components/messaging-system/targeting/Targeting.jsm
index 5e830b61b30c..6ed951b24fdb 100644
--- a/toolkit/components/messaging-system/targeting/Targeting.jsm
+++ b/toolkit/components/messaging-system/targeting/Targeting.jsm
@@ -134,7 +134,7 @@ class TargetingContext {
     const logUndesiredEvent = (event, key, prop) => {
       const value = key ? `${key}.${prop}` : prop;
       this._sendUndesiredEvent({ event, value });
-      Cu.reportError(`${event}: ${value}`);
+      console.error(`${event}: ${value}`);
     };
 
     return new Proxy(context, {
@@ -157,7 +157,7 @@ class TargetingContext {
           } catch (error) {
             logUndesiredEvent(ERROR_TYPES.ATTRIBUTE_ERROR, key, prop);
             reject(error);
-            Cu.reportError(error);
+            console.error(error);
           } finally {
             lazy.clearTimeout(timeout);
           }
diff --git a/toolkit/components/narrate/NarrateControls.jsm b/toolkit/components/narrate/NarrateControls.jsm
index ef091b7323b0..a597cd326716 100644
--- a/toolkit/components/narrate/NarrateControls.jsm
+++ b/toolkit/components/narrate/NarrateControls.jsm
@@ -271,7 +271,7 @@ NarrateControls.prototype = {
         this.narrator
           .start(options)
           .catch(err => {
-            Cu.reportError(`Narrate failed: ${err}.`);
+            console.error(`Narrate failed: ${err}.`);
           })
           .then(() => {
             this._updateSpeechControls(false);
diff --git a/toolkit/components/nimbus/ExperimentAPI.jsm b/toolkit/components/nimbus/ExperimentAPI.jsm
index 2c05318af116..e9421b48e335 100644
--- a/toolkit/components/nimbus/ExperimentAPI.jsm
+++ b/toolkit/components/nimbus/ExperimentAPI.jsm
@@ -46,7 +46,7 @@ function parseJSON(value) {
     try {
       return JSON.parse(value);
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
     }
   }
   return null;
@@ -112,7 +112,7 @@ const ExperimentAPI = {
         experimentData = this._store.getExperimentForFeature(featureId);
       }
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
     }
     if (experimentData) {
       return {
@@ -151,7 +151,7 @@ const ExperimentAPI = {
         }
       }
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
     }
     if (experimentData) {
       return {
@@ -194,7 +194,7 @@ const ExperimentAPI = {
         experiment = this._store.getExperimentForFeature(featureId);
       }
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
     }
 
     if (!experiment) {
@@ -276,7 +276,7 @@ const ExperimentAPI = {
     } catch (e) {
       // If an error occurs in .get(), an empty list is returned and the destructuring
       // assignment will throw.
-      Cu.reportError(e);
+      console.error(e);
       recipe = undefined;
     }
 
@@ -319,7 +319,7 @@ const ExperimentAPI = {
         }
       );
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
     }
     Glean.nimbusEvents.exposure.record({
       experiment: experimentSlug,
@@ -346,7 +346,7 @@ class _ExperimentFeature {
     this.prefGetters = {};
     this.manifest = manifest || lazy.FeatureManifest[featureId];
     if (!this.manifest) {
-      Cu.reportError(
+      console.error(
         `No manifest entry for ${featureId}. Please add one to toolkit/components/nimbus/FeatureManifest.js`
       );
     }
diff --git a/toolkit/components/nimbus/lib/ExperimentManager.jsm b/toolkit/components/nimbus/lib/ExperimentManager.jsm
index 6b9550065bde..cdd20e5b2d59 100644
--- a/toolkit/components/nimbus/lib/ExperimentManager.jsm
+++ b/toolkit/components/nimbus/lib/ExperimentManager.jsm
@@ -207,7 +207,7 @@ class _ExperimentManager {
           }
           this.unenroll(slug, reason);
         } catch (err) {
-          Cu.reportError(err);
+          console.error(err);
         }
       }
     }
diff --git a/toolkit/components/nimbus/lib/ExperimentStore.jsm b/toolkit/components/nimbus/lib/ExperimentStore.jsm
index 4b2155e12d3e..0f218d717e74 100644
--- a/toolkit/components/nimbus/lib/ExperimentStore.jsm
+++ b/toolkit/components/nimbus/lib/ExperimentStore.jsm
@@ -49,7 +49,7 @@ XPCOMUtils.defineLazyGetter(lazy, "syncDataStore", () => {
       try {
         branch.setStringPref(pref, JSON.stringify(value));
       } catch (e) {
-        Cu.reportError(e);
+        console.error(e);
       }
     },
     _trySetTypedPrefValue(pref, value) {
@@ -302,7 +302,7 @@ class ExperimentStore extends SharedDataMap {
     try {
       data = Object.values(this._data || {});
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
     }
 
     return data;
diff --git a/toolkit/components/nimbus/lib/RemoteSettingsExperimentLoader.jsm b/toolkit/components/nimbus/lib/RemoteSettingsExperimentLoader.jsm
index 300e82a72b7b..9c27dff85402 100644
--- a/toolkit/components/nimbus/lib/RemoteSettingsExperimentLoader.jsm
+++ b/toolkit/components/nimbus/lib/RemoteSettingsExperimentLoader.jsm
@@ -190,7 +190,7 @@ class _RemoteSettingsExperimentLoader {
       result = await targetingContext.evalWithDefault(jexlString);
     } catch (e) {
       lazy.log.debug("Targeting failed because of an error", e);
-      Cu.reportError(e);
+      console.error(e);
     }
     return result;
   }
@@ -254,7 +254,7 @@ class _RemoteSettingsExperimentLoader {
     } catch (e) {
       lazy.log.debug("Error getting recipes from remote settings.");
       loadingError = true;
-      Cu.reportError(e);
+      console.error(e);
     }
 
     let recipeValidator;
@@ -292,7 +292,7 @@ class _RemoteSettingsExperimentLoader {
         if (validationEnabled) {
           let validation = recipeValidator.validate(r);
           if (!validation.valid) {
-            Cu.reportError(
+            console.error(
               `Could not validate experiment recipe ${r.id}: ${JSON.stringify(
                 validation.errors,
                 undefined,
@@ -409,7 +409,7 @@ class _RemoteSettingsExperimentLoader {
           emptyListFallback: false,
         });
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
       throw new Error("Error getting recipes from remote settings.");
     }
 
@@ -488,9 +488,7 @@ class _RemoteSettingsExperimentLoader {
       for (const feature of features) {
         const { featureId, value } = feature;
         if (!lazy.NimbusFeatures[featureId]) {
-          Cu.reportError(
-            `Experiment ${id} has unknown featureId: ${featureId}`
-          );
+          console.error(`Experiment ${id} has unknown featureId: ${featureId}`);
 
           invalidFeatureIds.add(featureId);
           continue;
@@ -525,7 +523,7 @@ class _RemoteSettingsExperimentLoader {
 
         const result = validator.validate(value);
         if (!result.valid) {
-          Cu.reportError(
+          console.error(
             `Experiment ${id} branch ${branchIdx} feature ${featureId} does not validate: ${JSON.stringify(
               result.errors,
               undefined,
@@ -573,7 +571,7 @@ class _RemoteSettingsExperimentLoader {
 
         default:
           // NB: Experimenter doesn't outright reject invalid types either.
-          Cu.reportError(
+          console.error(
             `Feature ID ${featureId} has variable ${varName} with invalid FML type: ${prop.type}`
           );
           break;
diff --git a/toolkit/components/nimbus/lib/SharedDataMap.jsm b/toolkit/components/nimbus/lib/SharedDataMap.jsm
index c5bb9df26ac7..7817f5d6259d 100644
--- a/toolkit/components/nimbus/lib/SharedDataMap.jsm
+++ b/toolkit/components/nimbus/lib/SharedDataMap.jsm
@@ -42,13 +42,13 @@ class SharedDataMap extends EventEmitter {
             const profileDir = Services.dirsvc.get("ProfD", Ci.nsIFile).path;
             path = PathUtils.join(profileDir, `${sharedDataKey}.json`);
           } catch (e) {
-            Cu.reportError(e);
+            console.error(e);
           }
         }
         try {
           store = new lazy.JSONFile({ path });
         } catch (e) {
-          Cu.reportError(e);
+          console.error(e);
         }
         return store;
       });
@@ -66,7 +66,7 @@ class SharedDataMap extends EventEmitter {
         this._syncToChildren({ flush: true });
         this._checkIfReady();
       } catch (e) {
-        Cu.reportError(e);
+        console.error(e);
       }
     }
   }
diff --git a/toolkit/components/normandy/Normandy.jsm b/toolkit/components/normandy/Normandy.jsm
index facd89def787..ec969a5f4a81 100644
--- a/toolkit/components/normandy/Normandy.jsm
+++ b/toolkit/components/normandy/Normandy.jsm
@@ -234,7 +234,7 @@ var Normandy = {
         targetPrefType !== Services.prefs.PREF_INVALID &&
         targetPrefType !== sourcePrefType
       ) {
-        Cu.reportError(
+        console.error(
           new Error(
             `Error setting startup pref ${prefName}; pref type does not match.`
           )
@@ -274,7 +274,7 @@ var Normandy = {
           originalValues[prefName] = null;
         } else {
           // Unexpected error, report it and move on
-          Cu.reportError(e);
+          console.error(e);
           continue;
         }
       }
@@ -301,7 +301,7 @@ var Normandy = {
         }
         default: {
           // This should never happen.
-          Cu.reportError(
+          console.error(
             new Error(
               `Error getting startup pref ${prefName}; unexpected value type ${sourcePrefType}.`
             )
diff --git a/toolkit/components/normandy/actions/BaseAction.jsm b/toolkit/components/normandy/actions/BaseAction.jsm
index b8c17a3e2e2d..a06ae385fd7f 100644
--- a/toolkit/components/normandy/actions/BaseAction.jsm
+++ b/toolkit/components/normandy/actions/BaseAction.jsm
@@ -89,14 +89,12 @@ class BaseAction {
         break;
       }
       default: {
-        Cu.reportError(
-          new Error("BaseAction.fail() called at unexpected time")
-        );
+        console.error(new Error("BaseAction.fail() called at unexpected time"));
       }
     }
     this.state = BaseAction.STATE_FAILED;
     this.lastError = err;
-    Cu.reportError(err);
+    console.error(err);
   }
 
   // Gets the name of the action. Does not necessarily match the
@@ -170,7 +168,7 @@ class BaseAction {
       try {
         recipe.arguments = this.validateArguments(recipe.arguments);
       } catch (error) {
-        Cu.reportError(error);
+        console.error(error);
         uptakeResult = Uptake.RECIPE_EXECUTION_ERROR;
         suitability = BaseAction.suitability.ARGUMENTS_INVALID;
       }
@@ -179,7 +177,7 @@ class BaseAction {
     try {
       await this._processRecipe(recipe, suitability);
     } catch (err) {
-      Cu.reportError(err);
+      console.error(err);
       uptakeResult = Uptake.RECIPE_EXECUTION_ERROR;
     }
     Uptake.reportRecipe(recipe, uptakeResult);
@@ -249,7 +247,7 @@ class BaseAction {
           }
 
           this.lastError = err;
-          Cu.reportError(err);
+          console.error(err);
         }
         break;
       }
diff --git a/toolkit/components/normandy/actions/BranchedAddonStudyAction.jsm b/toolkit/components/normandy/actions/BranchedAddonStudyAction.jsm
index 7ac3f30ef385..1b29ccf4371c 100644
--- a/toolkit/components/normandy/actions/BranchedAddonStudyAction.jsm
+++ b/toolkit/components/normandy/actions/BranchedAddonStudyAction.jsm
@@ -229,7 +229,7 @@ class BranchedAddonStudyAction extends BaseStudyAction {
           try {
             await this.unenroll(study.recipeId, "recipe-not-seen");
           } catch (err) {
-            Cu.reportError(err);
+            console.error(err);
           }
         }
       }
diff --git a/toolkit/components/normandy/actions/PreferenceRolloutAction.jsm b/toolkit/components/normandy/actions/PreferenceRolloutAction.jsm
index dc878dd43dfe..90c54775ed4b 100644
--- a/toolkit/components/normandy/actions/PreferenceRolloutAction.jsm
+++ b/toolkit/components/normandy/actions/PreferenceRolloutAction.jsm
@@ -114,7 +114,7 @@ class PreferenceRolloutAction extends BaseAction {
             break;
           }
           default: {
-            Cu.reportError(
+            console.error(
               new Error(
                 `Updated pref rollout in unexpected state: ${existingRollout.state}`
               )
diff --git a/toolkit/components/normandy/lib/AddonStudies.jsm b/toolkit/components/normandy/lib/AddonStudies.jsm
index 4cc94418b83b..25a47534fab0 100644
--- a/toolkit/components/normandy/lib/AddonStudies.jsm
+++ b/toolkit/components/normandy/lib/AddonStudies.jsm
@@ -486,7 +486,7 @@ var AddonStudies = {
       try {
         await cb(reason);
       } catch (err) {
-        Cu.reportError(err);
+        console.error(err);
       }
     }
 
diff --git a/toolkit/components/normandy/lib/CleanupManager.jsm b/toolkit/components/normandy/lib/CleanupManager.jsm
index 7b3d28a51eb3..e632221b7b90 100644
--- a/toolkit/components/normandy/lib/CleanupManager.jsm
+++ b/toolkit/components/normandy/lib/CleanupManager.jsm
@@ -33,7 +33,7 @@ class CleanupManagerClass {
           try {
             await handler();
           } catch (ex) {
-            Cu.reportError(ex);
+            console.error(ex);
           }
         }
       })();
diff --git a/toolkit/components/normandy/lib/ShieldPreferences.jsm b/toolkit/components/normandy/lib/ShieldPreferences.jsm
index 9dea64cd92eb..fc97903cfc5e 100644
--- a/toolkit/components/normandy/lib/ShieldPreferences.jsm
+++ b/toolkit/components/normandy/lib/ShieldPreferences.jsm
@@ -74,7 +74,7 @@ var ShieldPreferences = {
 
           const allPromises = studyPromises
             .concat(experimentPromises)
-            .map(p => p && p.catch(err => Cu.reportError(err)));
+            .map(p => p && p.catch(err => console.error(err)));
           await Promise.all(allPromises);
         }
         break;
diff --git a/toolkit/components/passwordmgr/FirefoxRelay.jsm b/toolkit/components/passwordmgr/FirefoxRelay.jsm
index a0beded4a0a4..f150c888946c 100644
--- a/toolkit/components/passwordmgr/FirefoxRelay.jsm
+++ b/toolkit/components/passwordmgr/FirefoxRelay.jsm
@@ -59,7 +59,7 @@ async function getRelayTokenAsync() {
   try {
     return await lazy.fxAccounts.getOAuthToken({ scope: config.scope });
   } catch (e) {
-    Cu.reportError(`There was an error getting the user's token: ${e.message}`);
+    console.error(`There was an error getting the user's token: ${e.message}`);
     return undefined;
   }
 }
diff --git a/toolkit/components/passwordmgr/LoginManagerChild.jsm b/toolkit/components/passwordmgr/LoginManagerChild.jsm
index 051226174847..d00c0cb7d16a 100644
--- a/toolkit/components/passwordmgr/LoginManagerChild.jsm
+++ b/toolkit/components/passwordmgr/LoginManagerChild.jsm
@@ -2020,7 +2020,7 @@ class LoginManagerChild extends JSWindowActorChild {
 
     this._getLoginDataFromParent(form, { showPrimaryPassword: true })
       .then(this.loginsFound.bind(this))
-      .catch(Cu.reportError);
+      .catch(console.error);
   }
 
   isPasswordGenerationForcedOn(passwordField) {
@@ -2203,7 +2203,7 @@ class LoginManagerChild extends JSWindowActorChild {
               userTriggered: true,
             });
           })
-          .catch(Cu.reportError);
+          .catch(console.error);
         // Use `loginGUID !== null` to distinguish whether this is called when the
         // field is filled or tabbed away from. For the latter, don't highlight the field.
       } else if (loginGUID !== null) {
diff --git a/toolkit/components/passwordmgr/LoginManagerContextMenu.jsm b/toolkit/components/passwordmgr/LoginManagerContextMenu.jsm
index 7fb24a6397b6..fa2d50206d3b 100644
--- a/toolkit/components/passwordmgr/LoginManagerContextMenu.jsm
+++ b/toolkit/components/passwordmgr/LoginManagerContextMenu.jsm
@@ -207,7 +207,7 @@ const LoginManagerContextMenu = {
         loginFormOrigin: formOrigin,
         login,
       })
-      .catch(Cu.reportError);
+      .catch(console.error);
   },
 
   /**
diff --git a/toolkit/components/passwordmgr/storage-json.js b/toolkit/components/passwordmgr/storage-json.js
index fddf5849c985..668ed64775ac 100644
--- a/toolkit/components/passwordmgr/storage-json.js
+++ b/toolkit/components/passwordmgr/storage-json.js
@@ -84,7 +84,7 @@ class LoginManagerStorage_json {
         // Load the data asynchronously.
         this.log(`Opening database at ${this._store.path}.`);
         await this._store.load();
-      })().catch(Cu.reportError);
+      })().catch(console.error);
     } catch (e) {
       this.log(`Initialization failed ${e.name}.`);
       throw new Error("Initialization failed");
diff --git a/toolkit/components/pdfjs/content/PdfStreamConverter.jsm b/toolkit/components/pdfjs/content/PdfStreamConverter.jsm
index 6611b34bbe24..93c84acb6f45 100644
--- a/toolkit/components/pdfjs/content/PdfStreamConverter.jsm
+++ b/toolkit/components/pdfjs/content/PdfStreamConverter.jsm
@@ -288,7 +288,7 @@ class ChromeActions {
     } catch (err) {
       // If there's an error here, it means that something is really wrong
       // on pdf.js side during sandbox initialization phase.
-      Cu.reportError(err);
+      console.error(err);
       return sendResp(false);
     }
 
@@ -967,7 +967,7 @@ PdfStreamConverter.prototype = {
     rv.shouldOpen = true;
     // Log that we're doing this to help debug issues if people end up being
     // surprised by this behaviour.
-    Cu.reportError("Found unusable PDF preferences. Fixing back to PDF.js");
+    console.error("Found unusable PDF preferences. Fixing back to PDF.js");
 
     mime.preferredAction = Ci.nsIHandlerInfo.handleInternally;
     mime.alwaysAskBeforeHandling = false;
diff --git a/toolkit/components/places/Bookmarks.sys.mjs b/toolkit/components/places/Bookmarks.sys.mjs
index 93342b40c065..f9e44456160e 100644
--- a/toolkit/components/places/Bookmarks.sys.mjs
+++ b/toolkit/components/places/Bookmarks.sys.mjs
@@ -840,7 +840,7 @@ export var Bookmarks = Object.freeze({
           ) {
             // ...though we don't wait for the calculation.
             updateFrecency(db, [item.url, updatedItem.url]).catch(
-              Cu.reportError
+              console.error
             );
           }
 
@@ -1403,7 +1403,7 @@ export var Bookmarks = Object.freeze({
         // We don't wait for the frecency calculation.
         if (urls && urls.length) {
           await lazy.PlacesUtils.keywords.eraseEverything();
-          updateFrecency(db, urls).catch(Cu.reportError);
+          updateFrecency(db, urls).catch(console.error);
         }
       }
     );
@@ -2186,7 +2186,7 @@ function insertBookmark(item, parent) {
       // If not a tag recalculate frecency...
       if (item.type == Bookmarks.TYPE_BOOKMARK && !isTagging) {
         // ...though we don't wait for the calculation.
-        updateFrecency(db, [item.url]).catch(Cu.reportError);
+        updateFrecency(db, [item.url]).catch(console.error);
       }
 
       return item;
@@ -2256,7 +2256,7 @@ function insertBookmarkTree(items, source, parent, urls, lastAddedForParent) {
       });
 
       // We don't wait for the frecency calculation.
-      updateFrecency(db, urls).catch(Cu.reportError);
+      updateFrecency(db, urls).catch(console.error);
 
       return items;
     }
@@ -2778,7 +2778,7 @@ function removeBookmarks(items, options) {
 
       if (urls.length) {
         await lazy.PlacesUtils.keywords.removeFromURLsIfNotBookmarked(urls);
-        updateFrecency(db, urls).catch(Cu.reportError);
+        updateFrecency(db, urls).catch(console.error);
       }
     }
   );
diff --git a/toolkit/components/places/History.sys.mjs b/toolkit/components/places/History.sys.mjs
index e43937a34826..26e9e89cbc32 100644
--- a/toolkit/components/places/History.sys.mjs
+++ b/toolkit/components/places/History.sys.mjs
@@ -1100,7 +1100,7 @@ var notifyCleanup = async function(db, pages, transitionType = 0) {
             await Promise.resolve();
           }
         })
-        .catch(Cu.reportError);
+        .catch(console.error);
     }
   }
 
diff --git a/toolkit/components/places/PlacesExpiration.sys.mjs b/toolkit/components/places/PlacesExpiration.sys.mjs
index e9f8238d8025..131d9fddcdf0 100644
--- a/toolkit/components/places/PlacesExpiration.sys.mjs
+++ b/toolkit/components/places/PlacesExpiration.sys.mjs
@@ -485,7 +485,7 @@ export function nsPlacesExpiration() {
       // Expire daily on idle.
       Services.obs.addObserver(this, TOPIC_IDLE_DAILY, true);
     })
-    .catch(Cu.reportError);
+    .catch(console.error);
 
   // Block shutdown.
   let shutdownClient =
@@ -503,7 +503,7 @@ export function nsPlacesExpiration() {
     // If the database is dirty, we want to expire some entries, to speed up
     // the expiration process.
     if (this.status == STATUS.DIRTY) {
-      this._expire(ACTION.SHUTDOWN_DIRTY, LIMIT.LARGE).catch(Cu.reportError);
+      this._expire(ACTION.SHUTDOWN_DIRTY, LIMIT.LARGE).catch(console.error);
     }
   });
 }
@@ -522,19 +522,19 @@ nsPlacesExpiration.prototype = {
         // Everything should be expired without any limit.  If history is over
         // capacity then all existing visits will be expired.
         // Should only be used in tests, since may cause dataloss.
-        this._expire(ACTION.DEBUG, LIMIT.UNLIMITED).catch(Cu.reportError);
+        this._expire(ACTION.DEBUG, LIMIT.UNLIMITED).catch(console.error);
       } else if (limit > 0) {
         // The number of expired visits is limited by this amount.  It may be
         // used for testing purposes, like checking that limited queries work.
         this._debugLimit = limit;
-        this._expire(ACTION.DEBUG, LIMIT.DEBUG).catch(Cu.reportError);
+        this._expire(ACTION.DEBUG, LIMIT.DEBUG).catch(console.error);
       } else {
         // Any other value is intended as a 0 limit, that means no visits
         // will be expired.  Even if this doesn't touch visits, it will remove
         // any orphan pages, icons, annotations and similar from the database,
         // so it may be used for cleanup purposes.
         this._debugLimit = -1;
-        this._expire(ACTION.DEBUG, LIMIT.DEBUG).catch(Cu.reportError);
+        this._expire(ACTION.DEBUG, LIMIT.DEBUG).catch(console.error);
       }
     } else if (aTopic == TOPIC_IDLE_BEGIN) {
       // Stop the expiration timer.  We don't want to keep up expiring on idle
@@ -544,7 +544,7 @@ nsPlacesExpiration.prototype = {
         this._timer = null;
       }
       if (this.expireOnIdle) {
-        this._expire(ACTION.IDLE_DIRTY, LIMIT.LARGE).catch(Cu.reportError);
+        this._expire(ACTION.IDLE_DIRTY, LIMIT.LARGE).catch(console.error);
       }
     } else if (aTopic == TOPIC_IDLE_END) {
       // Restart the expiration timer.
@@ -552,7 +552,7 @@ nsPlacesExpiration.prototype = {
         this._newTimer();
       }
     } else if (aTopic == TOPIC_IDLE_DAILY) {
-      this._expire(ACTION.IDLE_DAILY, LIMIT.LARGE).catch(Cu.reportError);
+      this._expire(ACTION.IDLE_DAILY, LIMIT.LARGE).catch(console.error);
     } else if (aTopic == TOPIC_TESTING_MODE) {
       this._testingMode = true;
     } else if (aTopic == lazy.PlacesUtils.TOPIC_INIT_COMPLETE) {
@@ -582,7 +582,7 @@ nsPlacesExpiration.prototype = {
       // Adapt expiration aggressivity to the number of pages over the limit.
       let limit =
         overLimitPages > OVERLIMIT_PAGES_THRESHOLD ? LIMIT.LARGE : LIMIT.SMALL;
-      this._expire(action, limit).catch(Cu.reportError);
+      this._expire(action, limit).catch(console.error);
     }, 300000);
   },
 
diff --git a/toolkit/components/places/PlacesUtils.sys.mjs b/toolkit/components/places/PlacesUtils.sys.mjs
index 478c12372ba8..f964075f5c63 100644
--- a/toolkit/components/places/PlacesUtils.sys.mjs
+++ b/toolkit/components/places/PlacesUtils.sys.mjs
@@ -2152,7 +2152,7 @@ function setupDbForShutdown(conn, name) {
         conn.close();
         reject(ex);
       }
-    }).catch(Cu.reportError);
+    }).catch(console.error);
 
     // Make sure that Sqlite.sys.mjs doesn't close until we are done
     // with the high-level connection.
@@ -2177,7 +2177,7 @@ XPCOMUtils.defineLazyGetter(lazy, "gAsyncDBConnPromised", () =>
       setupDbForShutdown(conn, "PlacesUtils read-only connection");
       return conn;
     })
-    .catch(Cu.reportError)
+    .catch(console.error)
 );
 
 XPCOMUtils.defineLazyGetter(lazy, "gAsyncDBWrapperPromised", () =>
@@ -2188,7 +2188,7 @@ XPCOMUtils.defineLazyGetter(lazy, "gAsyncDBWrapperPromised", () =>
       setupDbForShutdown(conn, "PlacesUtils wrapped connection");
       return conn;
     })
-    .catch(Cu.reportError)
+    .catch(console.error)
 );
 
 var gAsyncDBLargeCacheConnDeferred = PromiseUtils.defer();
@@ -2225,7 +2225,7 @@ XPCOMUtils.defineLazyGetter(lazy, "gAsyncDBLargeCacheConnPromised", () =>
       gAsyncDBLargeCacheConnDeferred.resolve(conn);
       return conn;
     })
-    .catch(Cu.reportError)
+    .catch(console.error)
 );
 
 /**
diff --git a/toolkit/components/places/TaggingService.sys.mjs b/toolkit/components/places/TaggingService.sys.mjs
index e55df786f2a2..77222d727f2b 100644
--- a/toolkit/components/places/TaggingService.sys.mjs
+++ b/toolkit/components/places/TaggingService.sys.mjs
@@ -550,7 +550,7 @@ TagAutoCompleteSearch.prototype = {
       this._search.cancel();
     }
     this._search = new TagSearch(searchString, this, listener);
-    this._search.start().catch(Cu.reportError);
+    this._search.start().catch(console.error);
   },
 
   /**
diff --git a/toolkit/components/printing/content/print.js b/toolkit/components/printing/content/print.js
index a87826e7e057..4b79ab6b4d7d 100644
--- a/toolkit/components/printing/content/print.js
+++ b/toolkit/components/printing/content/print.js
@@ -84,9 +84,7 @@ function cancelDeferredTasks() {
 document.addEventListener(
   "DOMContentLoaded",
   e => {
-    window._initialized = PrintEventHandler.init().catch(e =>
-      Cu.reportError(e)
-    );
+    window._initialized = PrintEventHandler.init().catch(e => console.error(e));
     ourBrowser.setAttribute("flex", "0");
     ourBrowser.setAttribute("selectmenuconstrained", "false");
     ourBrowser.classList.add("printSettingsBrowser");
@@ -427,7 +425,7 @@ var PrintEventHandler = {
       let bc = this.printPreviewEl.currentBrowsingContext;
       await this._doPrint(bc, settings);
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
     }
 
     if (settings.printerName == PrintUtils.SAVE_TO_PDF_PRINTER) {
@@ -862,7 +860,7 @@ var PrintEventHandler = {
       }));
     } catch (e) {
       this.reportPrintingError("PRINT_PREVIEW");
-      Cu.reportError(e);
+      console.error(e);
       throw e;
     }
 
diff --git a/toolkit/components/printing/content/printUtils.js b/toolkit/components/printing/content/printUtils.js
index e15c4e43a71f..279e707c88ac 100644
--- a/toolkit/components/printing/content/printUtils.js
+++ b/toolkit/components/printing/content/printUtils.js
@@ -78,7 +78,7 @@ var PrintUtils = {
       // Need the await for the try to trigger...
       return await sourceActor.sendQuery("PrintingSelection:HasSelection", {});
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
     }
     return false;
   },
@@ -203,7 +203,7 @@ var PrintUtils = {
       args
     );
     closedPromise.catch(e => {
-      Cu.reportError(e);
+      console.error(e);
     });
 
     let settingsBrowser = dialog._frame;
@@ -549,7 +549,7 @@ var PrintUtils = {
         );
       }
     } catch (e) {
-      Cu.reportError("PrintUtils.getPrintSettings failed: " + e + "\n");
+      console.error("PrintUtils.getPrintSettings failed: ", e, "\n");
     }
     return printSettings;
   },
diff --git a/toolkit/components/prompts/content/adjustableTitle.js b/toolkit/components/prompts/content/adjustableTitle.js
index 2614480bc267..bd9afd909aca 100644
--- a/toolkit/components/prompts/content/adjustableTitle.js
+++ b/toolkit/components/prompts/content/adjustableTitle.js
@@ -128,7 +128,7 @@ const AdjustableTitle = {
           !DOMException.isInstance(ex) ||
           ex.name != "NoModificationAllowedError"
         ) {
-          Cu.reportError(ex);
+          console.error(ex);
         }
         return;
       }
diff --git a/toolkit/components/prompts/content/selectDialog.js b/toolkit/components/prompts/content/selectDialog.js
index d079beb755cf..86809bc87983 100644
--- a/toolkit/components/prompts/content/selectDialog.js
+++ b/toolkit/components/prompts/content/selectDialog.js
@@ -20,7 +20,7 @@ function onDCL() {
 
   let promptType = propBag.getProperty("promptType");
   if (promptType != "select") {
-    Cu.reportError("selectDialog opened for unknown type: " + promptType);
+    console.error("selectDialog opened for unknown type: ", promptType);
     window.close();
   }
 
diff --git a/toolkit/components/prompts/src/CommonDialog.sys.mjs b/toolkit/components/prompts/src/CommonDialog.sys.mjs
index 3bcb60ded23a..a0812aa8eca2 100644
--- a/toolkit/components/prompts/src/CommonDialog.sys.mjs
+++ b/toolkit/components/prompts/src/CommonDialog.sys.mjs
@@ -99,8 +99,9 @@ CommonDialog.prototype = {
         this.ui.password1Label.setAttribute("value", "");
         break;
       default:
-        Cu.reportError(
-          "commonDialog opened for unknown type: " + this.args.promptType
+        console.error(
+          "commonDialog opened for unknown type: ",
+          this.args.promptType
         );
         throw new Error("unknown dialog type");
     }
@@ -234,7 +235,7 @@ CommonDialog.prototype = {
           .playEventSound(this.soundID);
       }
     } catch (e) {
-      Cu.reportError("Couldn't play common dialog event sound: " + e);
+      console.error("Couldn't play common dialog event sound: ", e);
     }
 
     if (commonDialogEl) {
diff --git a/toolkit/components/prompts/src/Prompter.sys.mjs b/toolkit/components/prompts/src/Prompter.sys.mjs
index a79f5b5527b3..c88a64fccc27 100644
--- a/toolkit/components/prompts/src/Prompter.sys.mjs
+++ b/toolkit/components/prompts/src/Prompter.sys.mjs
@@ -50,9 +50,7 @@ Prompter.prototype = {
         ].getService(Ci.nsIPromptFactory);
         return pwmgr.getPrompt(domWin, iid);
       } catch (e) {
-        Cu.reportError(
-          "nsPrompter: Delegation to password manager failed: " + e
-        );
+        console.error("nsPrompter: Delegation to password manager failed: ", e);
       }
     }
 
@@ -997,7 +995,7 @@ class ModalPrompter {
     ) {
       // Only show this error if we're not about to fall back again and show a different one.
       if (this.browsingContext?.associatedWindow?.gDialogBox) {
-        Cu.reportError(
+        console.error(
           "Prompter: Browser not available. Falling back to internal window prompt."
         );
       }
@@ -1009,7 +1007,7 @@ class ModalPrompter {
       (this.browsingContext?.isContent ||
         !this.browsingContext?.associatedWindow?.gDialogBox)
     ) {
-      Cu.reportError(
+      console.error(
         "Prompter: internal dialogs not available in this context. Falling back to window prompt."
       );
       modalType = MODAL_TYPE_WINDOW;
@@ -1067,7 +1065,7 @@ class ModalPrompter {
     // and thus not supported as tab or content prompts yet. See Bug 1622817.
     // Once they are integrated this override should be removed.
     if (args.promptType == "select" && this.modalType !== MODAL_TYPE_WINDOW) {
-      Cu.reportError(
+      console.error(
         "Prompter: 'select' prompts do not support tab/content prompting. Falling back to window prompt."
       );
       args.modalType = MODAL_TYPE_WINDOW;
diff --git a/toolkit/components/reader/AboutReader.jsm b/toolkit/components/reader/AboutReader.jsm
index 4bf04a710511..151cd02c796f 100644
--- a/toolkit/components/reader/AboutReader.jsm
+++ b/toolkit/components/reader/AboutReader.jsm
@@ -79,7 +79,7 @@ var AboutReader = function(
     if (Services.prefs.getBoolPref("reader.errors.includeURLs")) {
       errorMsg += " Tried to load: " + url + ".";
     }
-    Cu.reportError(errorMsg);
+    console.error(errorMsg);
     win.location.href = "about:blank";
     return;
   }
diff --git a/toolkit/components/reader/ReaderMode.jsm b/toolkit/components/reader/ReaderMode.jsm
index 1449338e2a61..fbfd59679632 100644
--- a/toolkit/components/reader/ReaderMode.jsm
+++ b/toolkit/components/reader/ReaderMode.jsm
@@ -143,7 +143,7 @@ var ReaderMode = {
         win.document.nodePrincipal.originAttributes
       );
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
       return;
     }
     let loadFlags = webNav.LOAD_FLAGS_DISALLOW_INHERIT_PRINCIPAL;
@@ -278,7 +278,7 @@ var ReaderMode = {
         return null;
       }
     } catch (ex) {
-      Cu.reportError(
+      console.error(
         new Error(`Couldn't create URI from ${url} to download: ${ex}`)
       );
       return null;
@@ -422,7 +422,7 @@ var ReaderMode = {
         options,
       ]);
     } catch (e) {
-      Cu.reportError("Error in ReaderWorker: " + e);
+      console.error("Error in ReaderWorker: ", e);
       histogram.add(PARSE_ERROR_WORKER);
     }
 
diff --git a/toolkit/components/remotebrowserutils/RemoteWebNavigation.jsm b/toolkit/components/remotebrowserutils/RemoteWebNavigation.jsm
index d68fe6c1ad15..fbefd4fbffbb 100644
--- a/toolkit/components/remotebrowserutils/RemoteWebNavigation.jsm
+++ b/toolkit/components/remotebrowserutils/RemoteWebNavigation.jsm
@@ -170,7 +170,7 @@ class RemoteWebNavigation {
     try {
       this._browser.sendMessageToActor(aMessage, aData, "WebNavigation");
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
     }
   }
 }
diff --git a/toolkit/components/remotepagemanager/MessagePort.jsm b/toolkit/components/remotepagemanager/MessagePort.jsm
index 5de2b78a3337..3abac6ec86b5 100644
--- a/toolkit/components/remotepagemanager/MessagePort.jsm
+++ b/toolkit/components/remotepagemanager/MessagePort.jsm
@@ -35,7 +35,7 @@ class MessageListener {
       try {
         listener(message);
       } catch (e) {
-        Cu.reportError(e);
+        console.error(e);
       }
     }
   }
@@ -179,7 +179,7 @@ class MessagePort {
 
     let deferred = this.requests[messagedata.requestID];
     if (!deferred) {
-      Cu.reportError("Received a response to an unknown request.");
+      console.error("Received a response to an unknown request.");
       return;
     }
 
diff --git a/toolkit/components/remotepagemanager/RemotePageManagerParent.jsm b/toolkit/components/remotepagemanager/RemotePageManagerParent.jsm
index 0dcedb8fb3bc..0cc32ac5aa27 100644
--- a/toolkit/components/remotepagemanager/RemotePageManagerParent.jsm
+++ b/toolkit/components/remotepagemanager/RemotePageManagerParent.jsm
@@ -112,7 +112,7 @@ class RemotePages {
         // Unless the port is in the process of unloading, something strange
         // happened but allow other ports to receive the message
         if (e.result !== Cr.NS_ERROR_NOT_INITIALIZED) {
-          Cu.reportError(e);
+          console.error(e);
         }
       }
     }
@@ -324,7 +324,7 @@ var RemotePageManagerInternal = {
   initPort({ target: browser, data: { url, portID } }) {
     let callback = this.pages.get(url);
     if (!callback) {
-      Cu.reportError("Unexpected remote page load: " + url);
+      console.error("Unexpected remote page load: ", url);
       return;
     }
 
diff --git a/toolkit/components/resistfingerprinting/RFPHelper.jsm b/toolkit/components/resistfingerprinting/RFPHelper.jsm
index 332fcc7a43e7..91194f5c84f5 100644
--- a/toolkit/components/resistfingerprinting/RFPHelper.jsm
+++ b/toolkit/components/resistfingerprinting/RFPHelper.jsm
@@ -334,7 +334,7 @@ class _RFPHelper {
   _parseLetterboxingDimensions(aPrefValue) {
     if (!aPrefValue || !aPrefValue.match(/^(?:\d+x\d+,\s*)*(?:\d+x\d+)$/)) {
       if (aPrefValue) {
-        Cu.reportError(
+        console.error(
           `Invalid pref value for ${kPrefLetterboxingDimensions}: ${aPrefValue}`
         );
       }
diff --git a/toolkit/components/satchel/FormHistoryStartup.sys.mjs b/toolkit/components/satchel/FormHistoryStartup.sys.mjs
index 05bfdf3ceeb2..2fe368e0c838 100644
--- a/toolkit/components/satchel/FormHistoryStartup.sys.mjs
+++ b/toolkit/components/satchel/FormHistoryStartup.sys.mjs
@@ -22,7 +22,7 @@ FormHistoryStartup.prototype = {
     switch (topic) {
       case "idle-daily":
       case "formhistory-expire-now":
-        lazy.FormHistory.expireOldEntries().catch(Cu.reportError);
+        lazy.FormHistory.expireOldEntries().catch(console.error);
         break;
       case "profile-after-change":
         this.init();
diff --git a/toolkit/components/telemetry/app/TelemetryScheduler.sys.mjs b/toolkit/components/telemetry/app/TelemetryScheduler.sys.mjs
index d35221e0d445..6eb07c50d8f2 100644
--- a/toolkit/components/telemetry/app/TelemetryScheduler.sys.mjs
+++ b/toolkit/components/telemetry/app/TelemetryScheduler.sys.mjs
@@ -121,7 +121,7 @@ export var TelemetryScheduler = {
       if (this._log) {
         this._log.error("shutdown - Already shut down");
       } else {
-        Cu.reportError("TelemetryScheduler.shutdown - Already shut down");
+        console.error("TelemetryScheduler.shutdown - Already shut down");
       }
       return;
     }
diff --git a/toolkit/components/thumbnails/BackgroundPageThumbs.jsm b/toolkit/components/thumbnails/BackgroundPageThumbs.jsm
index 1eff8ebb094b..be8f2a269a2d 100644
--- a/toolkit/components/thumbnails/BackgroundPageThumbs.jsm
+++ b/toolkit/components/thumbnails/BackgroundPageThumbs.jsm
@@ -395,9 +395,7 @@ const BackgroundPageThumbs = {
         return;
       }
 
-      Cu.reportError(
-        "BackgroundThumbnails remote process crashed - recovering"
-      );
+      console.error("BackgroundThumbnails remote process crashed - recovering");
       this._destroyBrowser();
       let curCapture = this._captureQueue.length ? this._captureQueue[0] : null;
       // we could retry the pending capture, but it's possible the crash
@@ -730,7 +728,7 @@ Capture.prototype = {
         try {
           callback.call(options, this.url, reason, info);
         } catch (err) {
-          Cu.reportError(err);
+          console.error(err);
         }
       }
 
diff --git a/toolkit/components/thumbnails/PageThumbUtils.jsm b/toolkit/components/thumbnails/PageThumbUtils.jsm
index fe5df93348a8..cc96c5ea3ab6 100644
--- a/toolkit/components/thumbnails/PageThumbUtils.jsm
+++ b/toolkit/components/thumbnails/PageThumbUtils.jsm
@@ -118,7 +118,7 @@ var PageThumbUtils = {
       utils.getScrollbarSize(false, sbWidth, sbHeight);
     } catch (e) {
       // This might fail if the window does not have a presShell.
-      Cu.reportError("Unable to get scrollbar size in determineCropSize.");
+      console.error("Unable to get scrollbar size in determineCropSize.");
       sbWidth.value = sbHeight.value = 0;
     }
 
@@ -313,7 +313,7 @@ var PageThumbUtils = {
       utils.getScrollbarSize(false, sbWidth, sbHeight);
     } catch (e) {
       // This might fail if the window does not have a presShell.
-      Cu.reportError("Unable to get scrollbar size in determineCropSize.");
+      console.error("Unable to get scrollbar size in determineCropSize.");
       sbWidth.value = sbHeight.value = 0;
     }
 
diff --git a/toolkit/components/thumbnails/PageThumbs.jsm b/toolkit/components/thumbnails/PageThumbs.jsm
index a203f3a749dd..d7fa188c3c29 100644
--- a/toolkit/components/thumbnails/PageThumbs.jsm
+++ b/toolkit/components/thumbnails/PageThumbs.jsm
@@ -205,7 +205,7 @@ var PageThumbs = {
             resolve(blob, this.contentType);
           });
         })
-        .catch(e => Cu.reportError(e));
+        .catch(e => console.error(e));
     });
   },
 
@@ -435,7 +435,7 @@ var PageThumbs = {
       let buffer = await TaskUtils.readBlob(blob);
       await this._store(originalURL, url, buffer, channelError);
     } catch (ex) {
-      Cu.reportError("Exception thrown during thumbnail capture: '" + ex + "'");
+      console.error("Exception thrown during thumbnail capture: '", ex, "'");
     }
   },
 
@@ -571,7 +571,7 @@ var PageThumbsStorage = {
       lazy.PageThumbsStorageService.path,
       { ignoreExisting: true },
     ]).catch(function onError(aReason) {
-      Cu.reportError("Could not create thumbnails directory" + aReason);
+      console.error("Could not create thumbnails directory", aReason);
     });
   },
 
diff --git a/toolkit/components/url-classifier/SafeBrowsing.jsm b/toolkit/components/url-classifier/SafeBrowsing.jsm
index 5c4a619e5592..232b00777519 100644
--- a/toolkit/components/url-classifier/SafeBrowsing.jsm
+++ b/toolkit/components/url-classifier/SafeBrowsing.jsm
@@ -385,7 +385,7 @@ var SafeBrowsing = {
       default:
         let err =
           "SafeBrowsing getReportURL() called with unknown kind: " + kind;
-        Cu.reportError(err);
+        console.error(err);
         throw err;
     }
 
diff --git a/toolkit/components/urlformatter/URLFormatter.jsm b/toolkit/components/urlformatter/URLFormatter.jsm
index 728debca0f18..22bf3429d47c 100644
--- a/toolkit/components/urlformatter/URLFormatter.jsm
+++ b/toolkit/components/urlformatter/URLFormatter.jsm
@@ -147,7 +147,7 @@ nsURLFormatterService.prototype = {
       if (aKey in _this._defaults) {
         return _this._defaults[aKey].call(_this);
       }
-      Cu.reportError("formatURL: Couldn't find value for key: " + aKey);
+      console.error("formatURL: Couldn't find value for key: ", aKey);
       return aMatch;
     };
     return aFormat.replace(/%([A-Z_]+)%/g, replacementCallback);
@@ -159,7 +159,7 @@ nsURLFormatterService.prototype = {
     try {
       format = Services.prefs.getStringPref(aPref);
     } catch (ex) {
-      Cu.reportError("formatURLPref: Couldn't get pref: " + aPref);
+      console.error("formatURLPref: Couldn't get pref: ", aPref);
       return "about:blank";
     }
 
diff --git a/toolkit/components/utils/ClientEnvironment.jsm b/toolkit/components/utils/ClientEnvironment.jsm
index 25ee0cea15ef..ccd4af897c72 100644
--- a/toolkit/components/utils/ClientEnvironment.jsm
+++ b/toolkit/components/utils/ClientEnvironment.jsm
@@ -80,7 +80,7 @@ class ClientEnvironmentBase {
     try {
       target.main = lazy.TelemetryController.getCurrentPingData();
     } catch (err) {
-      Cu.reportError(err);
+      console.error(err);
     }
 
     return new Proxy(target, {
diff --git a/toolkit/components/utils/WindowsVersionInfo.jsm b/toolkit/components/utils/WindowsVersionInfo.jsm
index 753bfe31e135..d582ed0e5b21 100644
--- a/toolkit/components/utils/WindowsVersionInfo.jsm
+++ b/toolkit/components/utils/WindowsVersionInfo.jsm
@@ -42,7 +42,7 @@ var WindowsVersionInfo = {
       if (throwOnError) {
         throw err;
       }
-      Cu.reportError(err);
+      console.error(err);
       return WindowsVersionInfo.UNKNOWN_VERSION_INFO;
     }
 
diff --git a/toolkit/components/viewsource/content/viewSourceUtils.js b/toolkit/components/viewsource/content/viewSourceUtils.js
index cf3093f255f2..b30f5137ed39 100644
--- a/toolkit/components/viewsource/content/viewSourceUtils.js
+++ b/toolkit/components/viewsource/content/viewSourceUtils.js
@@ -297,7 +297,7 @@ var gViewSourceUtils = {
         }
       } catch (ex) {
         // we failed loading it with the external editor.
-        Cu.reportError(ex);
+        console.error(ex);
         reject(data);
       }
     });
@@ -317,7 +317,7 @@ var gViewSourceUtils = {
 
       return editor;
     } catch (ex) {
-      Cu.reportError(ex);
+      console.error(ex);
     }
 
     return null;
@@ -373,7 +373,7 @@ var gViewSourceUtils = {
         this.resolve(this.data);
       } catch (ex) {
         // we failed loading it with the external editor.
-        Cu.reportError(ex);
+        console.error(ex);
         this.reject(this.data);
       } finally {
         this.destroy();
diff --git a/toolkit/content/aboutSupport.js b/toolkit/content/aboutSupport.js
index b1bffd0bce0f..0be6d3752ca3 100644
--- a/toolkit/content/aboutSupport.js
+++ b/toolkit/content/aboutSupport.js
@@ -38,8 +38,11 @@ window.addEventListener("load", function onload(event) {
         try {
           await snapshotFormatters[prop](snapshot[prop]);
         } catch (e) {
-          Cu.reportError(
-            "stack of snapshot error for about:support: " + e + ": " + e.stack
+          console.error(
+            "stack of snapshot error for about:support: ",
+            e,
+            ": ",
+            e.stack
           );
         }
       }
@@ -55,9 +58,7 @@ window.addEventListener("load", function onload(event) {
       $("update-history-row").hidden = true;
     }
   } catch (e) {
-    Cu.reportError(
-      "stack of load error for about:support: " + e + ": " + e.stack
-    );
+    console.error("stack of load error for about:support: ", e, ": ", e.stack);
   }
 });
 
diff --git a/toolkit/content/contentAreaUtils.js b/toolkit/content/contentAreaUtils.js
index 5a370ef1eabe..29cdeed640f3 100644
--- a/toolkit/content/contentAreaUtils.js
+++ b/toolkit/content/contentAreaUtils.js
@@ -342,7 +342,7 @@ function internalSave(
 
         continueSave();
       })
-      .catch(Cu.reportError);
+      .catch(console.error);
   }
 
   function continueSave() {
@@ -835,7 +835,7 @@ function DownloadURL(aURL, aFileName, aInitiatingDocument) {
     // Add the download to the list, allowing it to be managed.
     let list = await Downloads.getList(Downloads.ALL);
     list.add(download);
-  })().catch(Cu.reportError);
+  })().catch(console.error);
 }
 
 // We have no DOM, and can only save the URL as is.
diff --git a/toolkit/content/globalOverlay.js b/toolkit/content/globalOverlay.js
index c021bfe74024..718d3e6aaee4 100644
--- a/toolkit/content/globalOverlay.js
+++ b/toolkit/content/globalOverlay.js
@@ -113,9 +113,7 @@ function goUpdateCommand(aCommand) {
 
     goSetCommandEnabled(aCommand, enabled);
   } catch (e) {
-    Cu.reportError(
-      "An error occurred updating the " + aCommand + " command: " + e
-    );
+    console.error("An error occurred updating the ", aCommand, " command: ", e);
   }
 }
 
@@ -128,8 +126,11 @@ function goDoCommand(aCommand) {
       controller.doCommand(aCommand);
     }
   } catch (e) {
-    Cu.reportError(
-      "An error occurred executing the " + aCommand + " command: " + e
+    console.error(
+      "An error occurred executing the ",
+      aCommand,
+      " command: ",
+      e
     );
   }
 }
diff --git a/toolkit/content/preferencesBindings.js b/toolkit/content/preferencesBindings.js
index e2e6494f9a75..f7db86247a4c 100644
--- a/toolkit/content/preferencesBindings.js
+++ b/toolkit/content/preferencesBindings.js
@@ -240,7 +240,7 @@ const Preferences = (window.Preferences = (function() {
         });
         return aTarget.dispatchEvent(event);
       } catch (e) {
-        Cu.reportError(e);
+        console.error(e);
       }
       return false;
     },
@@ -441,7 +441,7 @@ const Preferences = (window.Preferences = (function() {
             return rv;
           }
         } catch (e) {
-          Cu.reportError(e);
+          console.error(e);
         }
       }
 
diff --git a/toolkit/content/tests/chrome/window_browser_drop.xhtml b/toolkit/content/tests/chrome/window_browser_drop.xhtml
index ab8cbacbeb47..7999f25ae310 100644
--- a/toolkit/content/tests/chrome/window_browser_drop.xhtml
+++ b/toolkit/content/tests/chrome/window_browser_drop.xhtml
@@ -45,7 +45,7 @@ function dropOnRemoteBrowserAsync(browser, data, shouldExpectStateChange) {
     } catch (ex) {
       if (shouldExpectStateChange) {
         ok(false, "Should not have gotten an exception from the dropped link handler, but got: " + ex);
-        Cu.reportError(ex);
+        console.error(ex);
       }
     }
 
diff --git a/toolkit/content/widgets/browser-custom-element.js b/toolkit/content/widgets/browser-custom-element.js
index 9417ecd8fd6d..5ce39981d107 100644
--- a/toolkit/content/widgets/browser-custom-element.js
+++ b/toolkit/content/widgets/browser-custom-element.js
@@ -1030,12 +1030,12 @@
               this.docShell.browsingContext.useGlobalHistory = true;
             } catch (ex) {
               // This can occur if the Places database is locked
-              Cu.reportError("Error enabling browser global history: " + ex);
+              console.error("Error enabling browser global history: ", ex);
             }
           }
         }
       } catch (e) {
-        Cu.reportError(e);
+        console.error(e);
       }
       try {
         // Ensures the securityUI is initialized.
diff --git a/toolkit/content/widgets/menu.js b/toolkit/content/widgets/menu.js
index 0ac0edc7ec97..acd8e51c5f3f 100644
--- a/toolkit/content/widgets/menu.js
+++ b/toolkit/content/widgets/menu.js
@@ -286,7 +286,7 @@
         }
         let key = document.getElementById(keyId);
         if (!key) {
-          Cu.reportError(
+          console.error(
             `Key ${keyId} of menuitem ${this.getAttribute("label")} ` +
               `could not be found`
           );
diff --git a/toolkit/content/widgets/text.js b/toolkit/content/widgets/text.js
index 654afd6c2cee..3ada26b6f540 100644
--- a/toolkit/content/widgets/text.js
+++ b/toolkit/content/widgets/text.js
@@ -336,7 +336,7 @@
             uri.scheme +
             ": link using \
                          the text-link binding.";
-          Cu.reportError(msg);
+          console.error(msg);
           return;
         }
 
@@ -352,7 +352,7 @@
           return;
         }
       } catch (ex) {
-        Cu.reportError(ex);
+        console.error(ex);
       }
 
       aEvent.preventDefault();
diff --git a/toolkit/crashreporter/CrashSubmit.jsm b/toolkit/crashreporter/CrashSubmit.jsm
index 417250541b80..c9a4f72497de 100644
--- a/toolkit/crashreporter/CrashSubmit.jsm
+++ b/toolkit/crashreporter/CrashSubmit.jsm
@@ -164,7 +164,7 @@ Submitter.prototype = {
         })
       );
     } catch (ex) {
-      Cu.reportError(ex);
+      console.error(ex);
     }
 
     this.notifyStatus(SUCCESS, ret);
@@ -542,7 +542,7 @@ var CrashSubmit = {
     try {
       dirIter = new lazy.OS.File.DirectoryIterator(pendingDir);
     } catch (ex) {
-      Cu.reportError(ex);
+      console.error(ex);
       throw ex;
     }
 
@@ -588,7 +588,7 @@ var CrashSubmit = {
         }
       }
     } catch (ex) {
-      Cu.reportError(ex);
+      console.error(ex);
       throw ex;
     } finally {
       dirIter.close();
@@ -636,7 +636,7 @@ var CrashSubmit = {
         }
       });
     } catch (ex) {
-      Cu.reportError(ex);
+      console.error(ex);
       throw ex;
     } finally {
       dirIter.close();
diff --git a/toolkit/crashreporter/content/crashes.js b/toolkit/crashreporter/content/crashes.js
index 89469f7dbe6d..8cb0551e2b7a 100644
--- a/toolkit/crashreporter/content/crashes.js
+++ b/toolkit/crashreporter/content/crashes.js
@@ -20,17 +20,17 @@ document.addEventListener("DOMContentLoaded", () => {
   document
     .getElementById("clearUnsubmittedReports")
     .addEventListener("click", () => {
-      clearUnsubmittedReports().catch(Cu.reportError);
+      clearUnsubmittedReports().catch(console.error);
     });
   document
     .getElementById("submitAllUnsubmittedReports")
     .addEventListener("click", () => {
-      submitAllUnsubmittedReports().catch(Cu.reportError);
+      submitAllUnsubmittedReports().catch(console.error);
     });
   document
     .getElementById("clearSubmittedReports")
     .addEventListener("click", () => {
-      clearSubmittedReports().catch(Cu.reportError);
+      clearSubmittedReports().catch(console.error);
     });
 });
 
diff --git a/toolkit/modules/AppMenuNotifications.sys.mjs b/toolkit/modules/AppMenuNotifications.sys.mjs
index 15a71b03eeb8..77487437ac7a 100644
--- a/toolkit/modules/AppMenuNotifications.sys.mjs
+++ b/toolkit/modules/AppMenuNotifications.sys.mjs
@@ -147,7 +147,7 @@ export var AppMenuNotifications = {
       try {
         action.callback(win, fromDoorhanger);
       } catch (error) {
-        Cu.reportError(error);
+        console.error(error);
       }
 
       dismiss = action.dismiss;
diff --git a/toolkit/modules/AsyncPrefs.sys.mjs b/toolkit/modules/AsyncPrefs.sys.mjs
index 583c0af1774f..3bbd27e47d9d 100644
--- a/toolkit/modules/AsyncPrefs.sys.mjs
+++ b/toolkit/modules/AsyncPrefs.sys.mjs
@@ -148,7 +148,7 @@ export class AsyncPrefsParent extends JSProcessActorParent {
     try {
       Services.prefs[methodToUse](pref, value);
     } catch (ex) {
-      Cu.reportError(ex);
+      console.error(ex);
       return Promise.reject(ex.message);
     }
 
@@ -164,7 +164,7 @@ export class AsyncPrefsParent extends JSProcessActorParent {
     try {
       Services.prefs.clearUserPref(pref);
     } catch (ex) {
-      Cu.reportError(ex);
+      console.error(ex);
       return Promise.reject(ex.message);
     }
 
diff --git a/toolkit/modules/BrowserUtils.sys.mjs b/toolkit/modules/BrowserUtils.sys.mjs
index 07e327cc4169..66d3ca8d2587 100644
--- a/toolkit/modules/BrowserUtils.sys.mjs
+++ b/toolkit/modules/BrowserUtils.sys.mjs
@@ -183,9 +183,7 @@ export var BrowserUtils = {
           }
           // otherwise, fall through...
         } catch (ex) {
-          Cu.reportError(
-            "Invalid blob URI passed to formatURIForDisplay: " + ex
-          );
+          console.error("Invalid blob URI passed to formatURIForDisplay: ", ex);
         }
       /* For blob URIs without an origin, fall through and use the data URI
        * logic (shows just "(data)", localized). */
@@ -217,7 +215,7 @@ export var BrowserUtils = {
             }
           }
         } catch (ex) {
-          Cu.reportError(ex);
+          console.error(ex);
         }
     }
     return uri.asciiHost || uri.spec;
diff --git a/toolkit/modules/CertUtils.sys.mjs b/toolkit/modules/CertUtils.sys.mjs
index 523d504abe59..b8f4a900afe4 100644
--- a/toolkit/modules/CertUtils.sys.mjs
+++ b/toolkit/modules/CertUtils.sys.mjs
@@ -72,7 +72,7 @@ function validateCert(aCertificate, aCerts) {
 
   if (!aCertificate) {
     const missingCertErr = "A required certificate was not present.";
-    Cu.reportError(missingCertErr);
+    console.error(missingCertErr);
     throw new Ce(missingCertErr, Cr.NS_ERROR_ILLEGAL_VALUE);
   }
 
@@ -113,7 +113,7 @@ function validateCert(aCertificate, aCerts) {
     errors.forEach(Cu.reportError.bind(Cu));
     const certCheckErr =
       "Certificate checks failed. See previous errors for details.";
-    Cu.reportError(certCheckErr);
+    console.error(certCheckErr);
     throw new Ce(certCheckErr, Cr.NS_ERROR_ILLEGAL_VALUE);
   }
 }
diff --git a/toolkit/modules/Console.sys.mjs b/toolkit/modules/Console.sys.mjs
index 41260b97675c..0f395313d9fa 100644
--- a/toolkit/modules/Console.sys.mjs
+++ b/toolkit/modules/Console.sys.mjs
@@ -563,7 +563,7 @@ function sendConsoleAPIMessage(aConsole, aLevel, aFrame, aArgs, aOptions = {}) {
       try {
         consoleEvent.groupName = Array.prototype.join.call(aArgs, " ");
       } catch (ex) {
-        Cu.reportError(ex);
+        console.error(ex);
         Cu.reportError(ex.stack);
         return;
       }
diff --git a/toolkit/modules/DeferredTask.sys.mjs b/toolkit/modules/DeferredTask.sys.mjs
index ca738e119ed9..b8f66a50da37 100644
--- a/toolkit/modules/DeferredTask.sys.mjs
+++ b/toolkit/modules/DeferredTask.sys.mjs
@@ -334,7 +334,7 @@ DeferredTask.prototype = {
         // Indicate that the execution of the task has finished.  This happens
         // synchronously with the previous state changes in the function.
         this._runningPromise = null;
-      })().catch(Cu.reportError)
+      })().catch(console.error)
     );
   },
 
@@ -346,7 +346,7 @@ DeferredTask.prototype = {
     try {
       await this._taskFn();
     } catch (ex) {
-      Cu.reportError(ex);
+      console.error(ex);
     } finally {
       ChromeUtils.addProfilerMarker(
         "DeferredTask",
diff --git a/toolkit/modules/Finder.sys.mjs b/toolkit/modules/Finder.sys.mjs
index fb117414fe9d..eb27a12cdf8b 100644
--- a/toolkit/modules/Finder.sys.mjs
+++ b/toolkit/modules/Finder.sys.mjs
@@ -459,7 +459,7 @@ Finder.prototype = {
           return;
         }
       } catch (ex) {
-        Cu.reportError(ex);
+        console.error(ex);
       }
     }
 
diff --git a/toolkit/modules/FinderHighlighter.sys.mjs b/toolkit/modules/FinderHighlighter.sys.mjs
index 3905bf1c77b2..425146646af6 100644
--- a/toolkit/modules/FinderHighlighter.sys.mjs
+++ b/toolkit/modules/FinderHighlighter.sys.mjs
@@ -412,7 +412,7 @@ FinderHighlighter.prototype = {
     try {
       window = this.getTopWindow(window);
     } catch (ex) {
-      Cu.reportError(ex);
+      console.error(ex);
       return;
     }
     let dict = this.getForWindow(window);
diff --git a/toolkit/modules/FinderIterator.sys.mjs b/toolkit/modules/FinderIterator.sys.mjs
index 4abf17c76e84..f09873bed8fb 100644
--- a/toolkit/modules/FinderIterator.sys.mjs
+++ b/toolkit/modules/FinderIterator.sys.mjs
@@ -179,7 +179,7 @@ export class FinderIterator {
         !this._areParamsEqual(this._currentParams, iterParams, allowDistance)
       ) {
         if (kDebug) {
-          Cu.reportError(
+          console.error(
             `We're currently iterating over '${this._currentParams.word}', not '${word}'\n` +
               new Error().stack
           );
@@ -363,7 +363,7 @@ export class FinderIterator {
       try {
         listener[callback](params);
       } catch (ex) {
-        Cu.reportError("FinderIterator Error: " + ex);
+        console.error("FinderIterator Error: ", ex);
       }
     }
   }
diff --git a/toolkit/modules/FinderParent.sys.mjs b/toolkit/modules/FinderParent.sys.mjs
index 91b3490c3e51..057bb4cb7c9d 100644
--- a/toolkit/modules/FinderParent.sys.mjs
+++ b/toolkit/modules/FinderParent.sys.mjs
@@ -87,11 +87,11 @@ FinderParent.prototype = {
         l[aCallback].apply(l, aArgs);
       } catch (e) {
         if (!l[aCallback]) {
-          Cu.reportError(
+          console.error(
             `Missing ${aCallback} callback on RemoteFinderListener`
           );
         } else {
-          Cu.reportError(e);
+          console.error(e);
         }
       }
     }
@@ -565,7 +565,7 @@ FinderParent.prototype = {
           return;
         }
       } catch (ex) {
-        Cu.reportError(ex);
+        console.error(ex);
       }
     }
 
diff --git a/toolkit/modules/IgnoreLists.sys.mjs b/toolkit/modules/IgnoreLists.sys.mjs
index d2553c915db6..62fd0bd2fe53 100644
--- a/toolkit/modules/IgnoreLists.sys.mjs
+++ b/toolkit/modules/IgnoreLists.sys.mjs
@@ -84,7 +84,7 @@ class IgnoreListsManager {
       }
       // Don't throw an error just log it, just continue with no data, and hopefully
       // a sync will fix things later on.
-      Cu.reportError(ex);
+      console.error(ex);
     }
     return result;
   }
diff --git a/toolkit/modules/InlineSpellChecker.sys.mjs b/toolkit/modules/InlineSpellChecker.sys.mjs
index 37f01f80194d..7d70c6a89a74 100644
--- a/toolkit/modules/InlineSpellChecker.sys.mjs
+++ b/toolkit/modules/InlineSpellChecker.sys.mjs
@@ -26,11 +26,11 @@ InlineSpellChecker.prototype = {
     if (this.mRemote) {
       // We shouldn't get here, but let's just recover instead of bricking the
       // menu by throwing exceptions:
-      Cu.reportError(new Error("Unexpected remote spellchecker present!"));
+      console.error(new Error("Unexpected remote spellchecker present!"));
       try {
         this.mRemote.uninit();
       } catch (ex) {
-        Cu.reportError(ex);
+        console.error(ex);
       }
       this.mRemote = null;
     }
diff --git a/toolkit/modules/Integration.sys.mjs b/toolkit/modules/Integration.sys.mjs
index 1df048cafdd7..89136c9d2bec 100644
--- a/toolkit/modules/Integration.sys.mjs
+++ b/toolkit/modules/Integration.sys.mjs
@@ -146,7 +146,7 @@ var IntegrationPoint = function() {
           " they change when new overrides are registered.",
         Cr.NS_ERROR_NO_INTERFACE
       );
-      Cu.reportError(ex);
+      console.error(ex);
       throw ex;
     },
   };
@@ -243,7 +243,7 @@ IntegrationPoint.prototype = {
         combined = Object.create(combined, descriptors);
       } catch (ex) {
         // Any error will result in the current override being skipped.
-        Cu.reportError(ex);
+        console.error(ex);
       }
     }
 
diff --git a/toolkit/modules/JSONFile.sys.mjs b/toolkit/modules/JSONFile.sys.mjs
index c9bd290de568..cea569c5794e 100644
--- a/toolkit/modules/JSONFile.sys.mjs
+++ b/toolkit/modules/JSONFile.sys.mjs
@@ -232,7 +232,7 @@ JSONFile.prototype = {
       let errorNo = ex.winLastError || ex.unixErrno;
       this._recordTelemetry("load", errorNo ? errorNo.toString() : "");
       if (!(DOMException.isInstance(ex) && ex.name == "NotFoundError")) {
-        Cu.reportError(ex);
+        console.error(ex);
 
         // Move the original file to a backup location, ignoring errors.
         try {
@@ -244,7 +244,7 @@ JSONFile.prototype = {
           await IOUtils.move(this.path, uniquePath);
           this._recordTelemetry("load", "invalid_json");
         } catch (e2) {
-          Cu.reportError(e2);
+          console.error(e2);
         }
       }
 
@@ -256,7 +256,7 @@ JSONFile.prototype = {
           await IOUtils.copy(this._options.backupFile, this.path);
         } catch (e) {
           if (!(DOMException.isInstance(e) && e.name == "NotFoundError")) {
-            Cu.reportError(e);
+            console.error(e);
           }
         }
 
@@ -275,7 +275,7 @@ JSONFile.prototype = {
           this._recordTelemetry("load", "used_backup");
         } catch (e3) {
           if (!(DOMException.isInstance(e3) && e3.name == "NotFoundError")) {
-            Cu.reportError(e3);
+            console.error(e3);
           }
         }
       }
@@ -337,7 +337,7 @@ JSONFile.prototype = {
           ex.result == Cr.NS_ERROR_FILE_NOT_FOUND
         )
       ) {
-        Cu.reportError(ex);
+        console.error(ex);
         // Move the original file to a backup location, ignoring errors.
         try {
           let originalFile = new lazy.FileUtils.File(this.path);
@@ -350,7 +350,7 @@ JSONFile.prototype = {
           backupFile.remove(false);
           originalFile.moveTo(backupFile.parent, backupFile.leafName);
         } catch (e2) {
-          Cu.reportError(e2);
+          console.error(e2);
         }
       }
 
@@ -364,7 +364,7 @@ JSONFile.prototype = {
           backupFile.copyTo(null, basename);
         } catch (e) {
           if (e.result != Cr.NS_ERROR_FILE_NOT_FOUND) {
-            Cu.reportError(e);
+            console.error(e);
           }
         }
 
@@ -390,7 +390,7 @@ JSONFile.prototype = {
           }
         } catch (e3) {
           if (e3.result != Cr.NS_ERROR_FILE_NOT_FOUND) {
-            Cu.reportError(e3);
+            console.error(e3);
           }
         }
       }
diff --git a/toolkit/modules/JsonSchema.sys.mjs b/toolkit/modules/JsonSchema.sys.mjs
index d4f7dfee1344..62b063ec8aff 100644
--- a/toolkit/modules/JsonSchema.sys.mjs
+++ b/toolkit/modules/JsonSchema.sys.mjs
@@ -93,7 +93,7 @@ class Validator {
   addSchema(schema, id) {
     const draft = detectSchemaDraft(schema, undefined);
     if (draft && this.#draft != draft) {
-      Cu.reportError(
+      console.error(
         `Adding a draft "${draft}" schema to a draft "${
           this.#draft
         }" validator.`
@@ -162,7 +162,7 @@ function detectSchemaDraft(schema, defaultDraft = "2019-09") {
       return "2020-12";
 
     default:
-      Cu.reportError(
+      console.error(
         `Unexpected $schema "${$schema}", defaulting to ${defaultDraft}.`
       );
       return defaultDraft;
diff --git a/toolkit/modules/KeywordUtils.sys.mjs b/toolkit/modules/KeywordUtils.sys.mjs
index d2386b45a50d..2765dd3ce969 100644
--- a/toolkit/modules/KeywordUtils.sys.mjs
+++ b/toolkit/modules/KeywordUtils.sys.mjs
@@ -53,7 +53,7 @@ export var KeywordUtils = {
         }
       } catch (ex) {
         // makeURI() throws if url is invalid.
-        Cu.reportError(ex);
+        console.error(ex);
       }
     }
 
diff --git a/toolkit/modules/NewTabUtils.sys.mjs b/toolkit/modules/NewTabUtils.sys.mjs
index 924f982fb8d0..e88f492a1e9b 100644
--- a/toolkit/modules/NewTabUtils.sys.mjs
+++ b/toolkit/modules/NewTabUtils.sys.mjs
@@ -137,10 +137,10 @@ function LinksStorage() {
   } catch (ex) {
     // Something went wrong in the update process, we can't recover from here,
     // so just clear the storage and start from scratch (dataloss!).
-    Cu.reportError(
+    console.error(
       "Unable to migrate the newTab storage to the current version. " +
-        "Restarting from scratch.\n" +
-        ex
+        "Restarting from scratch.\n",
+      ex
     );
     this.clear();
   }
@@ -560,7 +560,7 @@ var BlockedLinks = {
         try {
           obs[methodName](...args);
         } catch (err) {
-          Cu.reportError(err);
+          console.error(err);
         }
       }
     }
@@ -719,7 +719,7 @@ var PlacesProvider = {
         try {
           obs[aMethodName](this, aArg);
         } catch (err) {
-          Cu.reportError(err);
+          console.error(err);
         }
       }
     }
@@ -1018,7 +1018,7 @@ var ActivityStreamProvider = {
         return [];
       }
     } catch (e) {
-      Cu.reportError(e);
+      console.error(e);
       return [];
     }
     /* Extract relevant parts needed to show this card as a highlight:
@@ -2143,7 +2143,7 @@ var Links = {
         try {
           obs[methodName](this, ...args);
         } catch (err) {
-          Cu.reportError(err);
+          console.error(err);
         }
       }
     }
diff --git a/toolkit/modules/OsEnvironment.sys.mjs b/toolkit/modules/OsEnvironment.sys.mjs
index 6af5d9db0ca2..ef8db0b72ee1 100644
--- a/toolkit/modules/OsEnvironment.sys.mjs
+++ b/toolkit/modules/OsEnvironment.sys.mjs
@@ -56,7 +56,7 @@ export let OsEnvironment = {
     try {
       haveAppSourcesFeature = OsEnvironment.Policy.windowsVersionHasAppSourcesFeature();
     } catch (ex) {
-      Cu.reportError(ex);
+      console.error(ex);
       Services.telemetry.scalarSet(appSourceScalar, "Error");
       return;
     }
@@ -69,7 +69,7 @@ export let OsEnvironment = {
     try {
       allowedAppSources = OsEnvironment.Policy.getAllowedAppSources();
     } catch (ex) {
-      Cu.reportError(ex);
+      console.error(ex);
       Services.telemetry.scalarSet(appSourceScalar, "Error");
       return;
     }
diff --git a/toolkit/modules/PopupNotifications.sys.mjs b/toolkit/modules/PopupNotifications.sys.mjs
index 55025c624716..cff108982b10 100644
--- a/toolkit/modules/PopupNotifications.sys.mjs
+++ b/toolkit/modules/PopupNotifications.sys.mjs
@@ -644,7 +644,7 @@ PopupNotifications.prototype = {
    * temporarily be hidden while the given panel is showing.
    */
   suppressWhileOpen(panel) {
-    this._hidePanel().catch(Cu.reportError);
+    this._hidePanel().catch(console.error);
     panel.addEventListener("popuphidden", aEvent => {
       this._update();
     });
@@ -739,7 +739,7 @@ PopupNotifications.prototype = {
     // Notifications are suppressed, ensure that the panel is hidden.
     if (!this._suppress) {
       this._suppress = true;
-      this._hidePanel().catch(Cu.reportError);
+      this._hidePanel().catch(console.error);
     }
   },
 
@@ -947,10 +947,10 @@ PopupNotifications.prototype = {
         text.secondName = tmp;
       }
     } else if (array.length > 3) {
-      Cu.reportError(
+      console.error(
         "Unexpected array length encountered in " +
-          "_formatDescriptionMessage: " +
-          array.length
+          "_formatDescriptionMessage: ",
+        array.length
       );
     }
     return text;
@@ -1081,7 +1081,7 @@ PopupNotifications.prototype = {
           }
           popupnotification.setAttribute("origin", uri);
         } catch (e) {
-          Cu.reportError(e);
+          console.error(e);
           popupnotification.removeAttribute("origin");
         }
       } else {
@@ -1642,7 +1642,7 @@ PopupNotifications.prototype = {
     let other = otherBrowser.ownerGlobal.PopupNotifications;
     if (!other) {
       if (ourNotifications.length) {
-        Cu.reportError(
+        console.error(
           "unable to swap notifications: otherBrowser doesn't support notifications"
         );
       }
@@ -1695,7 +1695,7 @@ PopupNotifications.prototype = {
         return n.options.eventCallback.call(n, event, ...args);
       }
     } catch (error) {
-      Cu.reportError(error);
+      console.error(error);
     }
     return undefined;
   },
@@ -1905,7 +1905,7 @@ PopupNotifications.prototype = {
           event,
         });
       } catch (error) {
-        Cu.reportError(error);
+        console.error(error);
       }
 
       if (action.dismiss) {
@@ -1937,7 +1937,7 @@ PopupNotifications.prototype = {
         source: "menucommand",
       });
     } catch (error) {
-      Cu.reportError(error);
+      console.error(error);
     }
 
     if (target.action.dismiss) {
diff --git a/toolkit/modules/Preferences.sys.mjs b/toolkit/modules/Preferences.sys.mjs
index d4b78ae36357..83fa827c6adc 100644
--- a/toolkit/modules/Preferences.sys.mjs
+++ b/toolkit/modules/Preferences.sys.mjs
@@ -137,13 +137,12 @@ Preferences._set = function(prefName, prefValue) {
       }
       this._prefBranch.setIntPref(prefName, prefValue);
       if (prefValue % 1 != 0) {
-        Cu.reportError(
-          "Warning: setting the " +
-            prefName +
-            " pref to the " +
-            "non-integer number " +
-            prefValue +
-            " converted it " +
+        console.error(
+          "Warning: setting the ",
+          prefName,
+          " pref to the non-integer number ",
+          prefValue,
+          " converted it " +
             "to the integer number " +
             this.get(prefName) +
             "; to retain fractional precision, store non-integer " +
@@ -343,7 +342,7 @@ Preferences.ignore = function(prefName, callback, thisObject) {
     Preferences._prefBranch.removeObserver(fullPrefName, observer);
     observers.splice(observers.indexOf(observer), 1);
   } else {
-    Cu.reportError(
+    console.error(
       `Attempt to stop observing a preference "${prefName}" that's not being observed`
     );
   }
diff --git a/toolkit/modules/RemotePageAccessManager.sys.mjs b/toolkit/modules/RemotePageAccessManager.sys.mjs
index 3078644a450f..f21c7844be1e 100644
--- a/toolkit/modules/RemotePageAccessManager.sys.mjs
+++ b/toolkit/modules/RemotePageAccessManager.sys.mjs
@@ -279,11 +279,11 @@ export let RemotePageAccessManager = {
       aDocument
     );
     if (!accessMapForFeature) {
-      Cu.reportError(
-        "RemotePageAccessManager does not allow access to Feature: " +
-          aFeature +
-          " for: " +
-          aDocument.location
+      console.error(
+        "RemotePageAccessManager does not allow access to Feature: ",
+        aFeature,
+        " for: ",
+        aDocument.location
       );
 
       return false;
diff --git a/toolkit/modules/ServiceRequest.sys.mjs b/toolkit/modules/ServiceRequest.sys.mjs
index 9f3b0787ae54..ab3d9ceb42da 100644
--- a/toolkit/modules/ServiceRequest.sys.mjs
+++ b/toolkit/modules/ServiceRequest.sys.mjs
@@ -59,7 +59,7 @@ function recordEvent(service, source = {}) {
   } catch (err) {
     // If the telemetry throws just log the error so it doesn't break any
     // functionality.
-    Cu.reportError(err);
+    console.error(err);
   }
 }
 
diff --git a/toolkit/modules/ShortcutUtils.sys.mjs b/toolkit/modules/ShortcutUtils.sys.mjs
index a8a7b1a7740c..f27702aedae7 100644
--- a/toolkit/modules/ShortcutUtils.sys.mjs
+++ b/toolkit/modules/ShortcutUtils.sys.mjs
@@ -130,7 +130,7 @@ export var ShortcutUtils = {
         // Some keys might not exist in the locale file, which will throw.
         key = bundle.GetStringFromName(keyCode);
       } catch (ex) {
-        Cu.reportError("Error finding " + keyCode + ": " + ex);
+        console.error("Error finding ", keyCode, ": ", ex);
         key = keyCode.replace(/^VK_/, "");
       }
     } else {
diff --git a/toolkit/modules/SubDialog.sys.mjs b/toolkit/modules/SubDialog.sys.mjs
index 50c1a94e74b5..54b830433482 100644
--- a/toolkit/modules/SubDialog.sys.mjs
+++ b/toolkit/modules/SubDialog.sys.mjs
@@ -247,7 +247,7 @@ SubDialog.prototype = {
       try {
         this._closingCallback.call(null, aEvent);
       } catch (ex) {
-        Cu.reportError(ex);
+        console.error(ex);
       }
       this._closingCallback = null;
     }
@@ -275,7 +275,7 @@ SubDialog.prototype = {
         try {
           this._closedCallback.call(null, aEvent);
         } catch (ex) {
-          Cu.reportError(ex);
+          console.error(ex);
         }
         this._closedCallback = null;
       }
@@ -618,13 +618,12 @@ SubDialog.prototype = {
     let maxHeight = this._window.innerHeight - frameOverhead;
     // Do this with a frame height in pixels...
     if (!frameHeight.endsWith("px")) {
-      Cu.reportError(
-        "This dialog (" +
-          this._frame.contentWindow.location.href +
-          ") " +
-          "set a height in non-px-non-em units ('" +
-          frameHeight +
-          "'), " +
+      console.error(
+        "This dialog (",
+        this._frame.contentWindow.location.href,
+        ") set a height in non-px-non-em units ('",
+        frameHeight,
+        "'), " +
           "which is likely to lead to bad sizing in in-content preferences. " +
           "Please consider changing this."
       );
diff --git a/toolkit/modules/UpdateUtils.sys.mjs b/toolkit/modules/UpdateUtils.sys.mjs
index 643fc19b3dde..b7f8244bd995 100644
--- a/toolkit/modules/UpdateUtils.sys.mjs
+++ b/toolkit/modules/UpdateUtils.sys.mjs
@@ -57,7 +57,7 @@ export var UpdateUtils = {
           });
         }
       } catch (e) {
-        Cu.reportError(e);
+        console.error(e);
       }
     }
 
@@ -135,10 +135,9 @@ export var UpdateUtils = {
       }
     }
 
-    Cu.reportError(
-      FILE_UPDATE_LOCALE +
-        " file doesn't exist in either the " +
-        "application or GRE directories"
+    console.error(
+      FILE_UPDATE_LOCALE,
+      " file doesn't exist in either the application or GRE directories"
     );
 
     return (this._locale = null);
@@ -458,10 +457,10 @@ export var UpdateUtils = {
           await writeUpdateConfig(config);
           return config;
         } catch (e) {
-          Cu.reportError(
+          console.error(
             "UpdateUtils.writeUpdateConfigSetting: App update configuration " +
-              "file write failed. Exception: " +
-              e
+              "file write failed. Exception: ",
+            e
           );
           // Re-throw the error so the caller knows that writing the value in
           // the app update config file failed.
@@ -778,7 +777,7 @@ function readEffectiveValue(config, prefName) {
     if (prefTypeFns.isValid(config[prefName])) {
       return config[prefName];
     }
-    Cu.reportError(
+    console.error(
       `readEffectiveValue: Got invalid value for update config's` +
         ` '${prefName}' value: "${config[prefName]}"`
     );
@@ -813,7 +812,7 @@ function readDefaultValue(config, prefName) {
       if (prefTypeFns.isValid(defaults[prefName])) {
         return defaults[prefName];
       }
-      Cu.reportError(
+      console.error(
         `readEffectiveValue: Got invalid default value for update` +
           ` config's '${prefName}' value: "${defaults[prefName]}"`
       );
@@ -849,7 +848,7 @@ async function readUpdateConfig() {
           onMigrationSuccessful();
           return migrationConfig;
         } catch (e) {
-          Cu.reportError("readUpdateConfig: Migration failed: " + e);
+          console.error("readUpdateConfig: Migration failed: ", e);
         }
       }
     } else {
@@ -858,10 +857,10 @@ async function readUpdateConfig() {
       // it doesn't happen again.
       setUpdateConfigMigrationDone();
 
-      Cu.reportError(
+      console.error(
         "readUpdateConfig: Unable to read app update configuration file. " +
-          "Exception: " +
-          e
+          "Exception: ",
+        e
       );
     }
     return makeDefaultUpdateConfig();
@@ -948,9 +947,7 @@ function getMemoryMB() {
       memoryMB = Math.round(memoryMB / 1024 / 1024);
     }
   } catch (e) {
-    Cu.reportError(
-      "Error getting system info memsize property. Exception: " + e
-    );
+    console.error("Error getting system info memsize property. Exception: ", e);
   }
   return memoryMB;
 }
@@ -1009,7 +1006,7 @@ XPCOMUtils.defineLazyGetter(lazy, "gWinCPUArch", function aus_gWinCPUArch() {
   try {
     kernel32 = lazy.ctypes.open("Kernel32");
   } catch (e) {
-    Cu.reportError("Unable to open kernel32! Exception: " + e);
+    console.error("Unable to open kernel32! Exception: ", e);
   }
 
   if (kernel32) {
@@ -1040,7 +1037,7 @@ XPCOMUtils.defineLazyGetter(lazy, "gWinCPUArch", function aus_gWinCPUArch() {
           break;
       }
     } catch (e) {
-      Cu.reportError("Error getting processor architecture. Exception: " + e);
+      console.error("Error getting processor architecture. Exception: ", e);
     } finally {
       kernel32.close();
     }
@@ -1054,7 +1051,7 @@ XPCOMUtils.defineLazyGetter(UpdateUtils, "ABI", function() {
   try {
     abi = Services.appinfo.XPCOMABI;
   } catch (e) {
-    Cu.reportError("XPCOM ABI unknown");
+    console.error("XPCOM ABI unknown");
   }
 
   if (AppConstants.platform == "win") {
@@ -1078,7 +1075,7 @@ XPCOMUtils.defineLazyGetter(UpdateUtils, "OSVersion", function() {
       " " +
       Services.sysinfo.getProperty("version");
   } catch (e) {
-    Cu.reportError("OS Version unknown.");
+    console.error("OS Version unknown.");
   }
 
   if (osVersion) {
@@ -1092,9 +1089,7 @@ XPCOMUtils.defineLazyGetter(UpdateUtils, "OSVersion", function() {
         } = lazy.WindowsVersionInfo.get();
         osVersion += `.${servicePackMajor}.${servicePackMinor}.${buildNumber}`;
       } catch (err) {
-        Cu.reportError(
-          "Unable to retrieve windows version information: " + err
-        );
+        console.error("Unable to retrieve windows version information: ", err);
         osVersion += ".unknown";
       }
 
diff --git a/toolkit/modules/WebChannel.sys.mjs b/toolkit/modules/WebChannel.sys.mjs
index 730d96529b73..a2f2ccec99b7 100644
--- a/toolkit/modules/WebChannel.sys.mjs
+++ b/toolkit/modules/WebChannel.sys.mjs
@@ -26,7 +26,7 @@ export var WebChannelBroker = Object.create({
     if (!this._channelMap.has(channel)) {
       this._channelMap.set(channel);
     } else {
-      Cu.reportError("Failed to register the channel. Channel already exists.");
+      console.error("Failed to register the channel. Channel already exists.");
     }
   },
 
@@ -40,7 +40,7 @@ export var WebChannelBroker = Object.create({
    */
   unregisterChannel(channelToRemove) {
     if (!this._channelMap.delete(channelToRemove)) {
-      Cu.reportError("Failed to unregister the channel. Channel not found.");
+      console.error("Failed to unregister the channel. Channel not found.");
     }
   },
 
@@ -215,7 +215,7 @@ WebChannel.prototype = {
     if (message && browsingContext && principal) {
       let { currentWindowGlobal } = browsingContext;
       if (!currentWindowGlobal) {
-        Cu.reportError(
+        console.error(
           "Failed to send a WebChannel message. No currentWindowGlobal."
         );
         return;
@@ -229,9 +229,9 @@ WebChannel.prototype = {
           principal,
         });
     } else if (!message) {
-      Cu.reportError("Failed to send a WebChannel message. Message not set.");
+      console.error("Failed to send a WebChannel message. Message not set.");
     } else {
-      Cu.reportError("Failed to send a WebChannel message. Target invalid.");
+      console.error("Failed to send a WebChannel message. Target invalid.");
     }
   },
 
@@ -264,11 +264,11 @@ WebChannel.prototype = {
           },
           sendingContext
         );
-        Cu.reportError("Failed to execute WebChannel callback:");
-        Cu.reportError(ex);
+        console.error("Failed to execute WebChannel callback:");
+        console.error(ex);
       }
     } else {
-      Cu.reportError("No callback set for this channel.");
+      console.error("No callback set for this channel.");
     }
   },
 };
diff --git a/toolkit/modules/subprocess/subprocess_common.sys.mjs b/toolkit/modules/subprocess/subprocess_common.sys.mjs
index 873a2bc8ed9b..aa3a28fb7b1f 100644
--- a/toolkit/modules/subprocess/subprocess_common.sys.mjs
+++ b/toolkit/modules/subprocess/subprocess_common.sys.mjs
@@ -104,7 +104,7 @@ export class PromiseWorker extends ChromeWorker {
       try {
         listener(event.data);
       } catch (e) {
-        Cu.reportError(e);
+        console.error(e);
       }
     }
   }
diff --git a/toolkit/modules/tests/modules/PromiseTestUtils.sys.mjs b/toolkit/modules/tests/modules/PromiseTestUtils.sys.mjs
index f3169e014d9e..2286ac03da24 100644
--- a/toolkit/modules/tests/modules/PromiseTestUtils.sys.mjs
+++ b/toolkit/modules/tests/modules/PromiseTestUtils.sys.mjs
@@ -50,7 +50,7 @@ export var PromiseTestUtils = {
    */
   init() {
     if (this._initialized) {
-      Cu.reportError("This object was already initialized.");
+      console.error("This object was already initialized.");
       return;
     }
 
diff --git a/toolkit/mozapps/downloads/HelperAppDlg.jsm b/toolkit/mozapps/downloads/HelperAppDlg.jsm
index 870f2cec179c..5ec97a8771f5 100644
--- a/toolkit/mozapps/downloads/HelperAppDlg.jsm
+++ b/toolkit/mozapps/downloads/HelperAppDlg.jsm
@@ -417,7 +417,7 @@ nsUnknownContentTypeDialog.prototype = {
           aLauncher.saveDestinationAvailable(result, true);
         });
       });
-    })().catch(Cu.reportError);
+    })().catch(console.error);
   },
 
   getFinalLeafName(aLeafName, aFileExt) {