diff --git a/devtools/client/aboutdebugging/test/browser/head.js b/devtools/client/aboutdebugging/test/browser/head.js
index d61faab55301..5d78d66ad149 100644
--- a/devtools/client/aboutdebugging/test/browser/head.js
+++ b/devtools/client/aboutdebugging/test/browser/head.js
@@ -397,7 +397,7 @@ async function openProfilerDialog(client, doc) {
 function getThisFirefoxString(aboutDebuggingWindow) {
   const loader = aboutDebuggingWindow.getBrowserLoaderForWindow();
   const { l10n } = loader.require(
-    "devtools/client/aboutdebugging/src/modules/l10n"
+    "resource://devtools/client/aboutdebugging/src/modules/l10n.js"
   );
   return l10n.getString("about-debugging-this-firefox-runtime-name");
 }
diff --git a/devtools/client/framework/browser-toolbox/Launcher.sys.mjs b/devtools/client/framework/browser-toolbox/Launcher.sys.mjs
index 7db539d336be..8830a0771511 100644
--- a/devtools/client/framework/browser-toolbox/Launcher.sys.mjs
+++ b/devtools/client/framework/browser-toolbox/Launcher.sys.mjs
@@ -134,10 +134,10 @@ export class BrowserToolboxLauncher extends EventEmitter {
     // invisible to the debugger (unlike the usual loader settings).
     this.#loader = useDistinctSystemPrincipalLoader(this);
     const { DevToolsServer } = this.#loader.require(
-      "devtools/server/devtools-server"
+      "resource://devtools/server/devtools-server.js"
     );
     const { SocketListener } = this.#loader.require(
-      "devtools/shared/security/socket"
+      "resource://devtools/shared/security/socket.js"
     );
     this.#devToolsServer = DevToolsServer;
     dumpn("Created a separate loader instance for the DevToolsServer.");
diff --git a/devtools/client/framework/browser-toolbox/window.js b/devtools/client/framework/browser-toolbox/window.js
index 54279a801d2b..85a3eb4071c4 100644
--- a/devtools/client/framework/browser-toolbox/window.js
+++ b/devtools/client/framework/browser-toolbox/window.js
@@ -9,7 +9,7 @@ var { loader, require, DevToolsLoader } = ChromeUtils.import(
 );
 
 // Require this module to setup core modules
-loader.require("devtools/client/framework/devtools-browser");
+loader.require("resource://devtools/client/framework/devtools-browser.js");
 
 var { gDevTools } = require("resource://devtools/client/framework/devtools.js");
 var { Toolbox } = require("resource://devtools/client/framework/toolbox.js");
@@ -264,10 +264,10 @@ function installTestingServer() {
     invisibleToDebugger: true,
   });
   const { DevToolsServer } = testLoader.require(
-    "devtools/server/devtools-server"
+    "resource://devtools/server/devtools-server.js"
   );
   const { SocketListener } = testLoader.require(
-    "devtools/shared/security/socket"
+    "resource://devtools/shared/security/socket.js"
   );
 
   DevToolsServer.init();
diff --git a/devtools/client/framework/test/allocations/head.js b/devtools/client/framework/test/allocations/head.js
index c7c796960d42..57d3e6006f9d 100644
--- a/devtools/client/framework/test/allocations/head.js
+++ b/devtools/client/framework/test/allocations/head.js
@@ -19,7 +19,7 @@ let tracker;
     invisibleToDebugger: true,
   });
   const { allocationTracker } = loader.require(
-    "chrome://mochitests/content/browser/devtools/shared/test-helpers/allocation-tracker"
+    "chrome://mochitests/content/browser/devtools/shared/test-helpers/allocation-tracker.js"
   );
   tracker = allocationTracker({ watchDevToolsGlobals: true });
 }
@@ -93,7 +93,7 @@ async function startRecordingAllocations({
           invisibleToDebugger: true,
         });
         const { allocationTracker } = loader.require(
-          "chrome://mochitests/content/browser/devtools/shared/test-helpers/allocation-tracker"
+          "chrome://mochitests/content/browser/devtools/shared/test-helpers/allocation-tracker.js"
         );
         // We watch all globals in the content process, (instead of only DevTools global in parent process)
         // because we may easily leak web page objects, which aren't in DevTools global.
diff --git a/devtools/client/framework/test/browser_target_from_url.js b/devtools/client/framework/test/browser_target_from_url.js
index 960653709802..ea45319554cc 100644
--- a/devtools/client/framework/test/browser_target_from_url.js
+++ b/devtools/client/framework/test/browser_target_from_url.js
@@ -80,8 +80,12 @@ add_task(async function() {
 async function setupDevToolsServer(webSocket) {
   info("Create a separate loader instance for the DevToolsServer.");
   const loader = new DevToolsLoader();
-  const { DevToolsServer } = loader.require("devtools/server/devtools-server");
-  const { SocketListener } = loader.require("devtools/shared/security/socket");
+  const { DevToolsServer } = loader.require(
+    "resource://devtools/server/devtools-server.js"
+  );
+  const { SocketListener } = loader.require(
+    "resource://devtools/shared/security/socket.js"
+  );
 
   DevToolsServer.init();
   DevToolsServer.registerAllActors();
diff --git a/devtools/client/responsive/test/browser/head.js b/devtools/client/responsive/test/browser/head.js
index 9b4beabd8489..bffa7096b314 100644
--- a/devtools/client/responsive/test/browser/head.js
+++ b/devtools/client/responsive/test/browser/head.js
@@ -708,7 +708,7 @@ function testViewportDimensions(ui, w, h) {
 
 async function changeUserAgentInput(ui, value) {
   const { Simulate } = ui.toolWindow.require(
-    "devtools/client/shared/vendor/react-dom-test-utils"
+    "resource://devtools/client/shared/vendor/react-dom-test-utils.js"
   );
   const { document, store } = ui.toolWindow;
   const browser = ui.getViewportBrowser();
@@ -734,7 +734,7 @@ async function changeUserAgentInput(ui, value) {
  */
 function addDeviceInModal(ui, device) {
   const { Simulate } = ui.toolWindow.require(
-    "devtools/client/shared/vendor/react-dom-test-utils"
+    "resource://devtools/client/shared/vendor/react-dom-test-utils.js"
   );
   const { document, store } = ui.toolWindow;
 
@@ -777,7 +777,7 @@ function addDeviceInModal(ui, device) {
 
 async function editDeviceInModal(ui, device, newDevice) {
   const { Simulate } = ui.toolWindow.require(
-    "devtools/client/shared/vendor/react-dom-test-utils"
+    "resource://devtools/client/shared/vendor/react-dom-test-utils.js"
   );
   const { document, store } = ui.toolWindow;
 
diff --git a/devtools/client/shared/test/shared-head.js b/devtools/client/shared/test/shared-head.js
index 941929a0e205..f72cdc0cdb19 100644
--- a/devtools/client/shared/test/shared-head.js
+++ b/devtools/client/shared/test/shared-head.js
@@ -39,7 +39,7 @@ if (DEBUG_ALLOCATIONS) {
   });
 
   const { allocationTracker } = loader.require(
-    "devtools/shared/test-helpers/allocation-tracker"
+    "resource://devtools/shared/test-helpers/allocation-tracker.js"
   );
   const tracker = allocationTracker({ watchAllGlobals: true });
   registerCleanupFunction(() => {
diff --git a/devtools/client/webconsole/webconsole-ui.js b/devtools/client/webconsole/webconsole-ui.js
index b281c37683cc..561173b9f831 100644
--- a/devtools/client/webconsole/webconsole-ui.js
+++ b/devtools/client/webconsole/webconsole-ui.js
@@ -605,7 +605,7 @@ class WebConsoleUI {
     const WebConsoleWrapper = BrowserLoader({
       baseURI: "resource://devtools/client/webconsole/",
       window: this.window,
-    }).require("devtools/client/webconsole/webconsole-wrapper");
+    }).require("resource://devtools/client/webconsole/webconsole-wrapper.js");
 
     this.wrapper = new WebConsoleWrapper(
       this.outputNode,
diff --git a/devtools/server/actors/watcher/SessionDataHelpers.jsm b/devtools/server/actors/watcher/SessionDataHelpers.jsm
index 30e9358274f7..87fe4687f050 100644
--- a/devtools/server/actors/watcher/SessionDataHelpers.jsm
+++ b/devtools/server/actors/watcher/SessionDataHelpers.jsm
@@ -47,8 +47,9 @@ if (typeof module == "object") {
     const { loader } = ChromeUtils.import(
       "resource://devtools/shared/loader/Loader.jsm"
     );
-    return loader.require("devtools/server/actors/utils/event-breakpoints")
-      .validateEventBreakpoint;
+    return loader.require(
+      "resource://devtools/server/actors/utils/event-breakpoints.js"
+    ).validateEventBreakpoint;
   });
 }
 
diff --git a/devtools/server/connectors/js-window-actor/DevToolsFrameChild.sys.mjs b/devtools/server/connectors/js-window-actor/DevToolsFrameChild.sys.mjs
index ebf866680f34..5507f1b50d85 100644
--- a/devtools/server/connectors/js-window-actor/DevToolsFrameChild.sys.mjs
+++ b/devtools/server/connectors/js-window-actor/DevToolsFrameChild.sys.mjs
@@ -322,11 +322,11 @@ export class DevToolsFrameChild extends JSWindowActorChild {
         : Loader;
     }
     const { DevToolsServer } = this.loader.require(
-      "devtools/server/devtools-server"
+      "resource://devtools/server/devtools-server.js"
     );
 
     const { WindowGlobalTargetActor } = this.loader.require(
-      "devtools/server/actors/targets/window-global"
+      "resource://devtools/server/actors/targets/window-global.js"
     );
 
     DevToolsServer.init();
diff --git a/devtools/server/connectors/js-window-actor/DevToolsWorkerChild.sys.mjs b/devtools/server/connectors/js-window-actor/DevToolsWorkerChild.sys.mjs
index bfdb2e1b3018..5722581544db 100644
--- a/devtools/server/connectors/js-window-actor/DevToolsWorkerChild.sys.mjs
+++ b/devtools/server/connectors/js-window-actor/DevToolsWorkerChild.sys.mjs
@@ -21,7 +21,7 @@ XPCOMUtils.defineLazyGetter(lazy, "Loader", () =>
 );
 
 XPCOMUtils.defineLazyGetter(lazy, "DevToolsUtils", () =>
-  lazy.Loader.require("devtools/shared/DevToolsUtils")
+  lazy.Loader.require("resource://devtools/shared/DevToolsUtils.js")
 );
 XPCOMUtils.defineLazyModuleGetters(lazy, {
   SessionDataHelpers:
@@ -267,7 +267,7 @@ export class DevToolsWorkerChild extends JSWindowActorChild {
 
   _createConnection(forwardingPrefix) {
     const { DevToolsServer } = lazy.Loader.require(
-      "devtools/server/devtools-server"
+      "resource://devtools/server/devtools-server.js"
     );
 
     DevToolsServer.init();
@@ -322,7 +322,7 @@ export class DevToolsWorkerChild extends JSWindowActorChild {
 
     // Create the actual worker target actor, in the worker thread.
     const { connectToWorker } = lazy.Loader.require(
-      "devtools/server/connectors/worker-connector"
+      "resource://devtools/server/connectors/worker-connector.js"
     );
 
     const onConnectToWorker = connectToWorker(
diff --git a/devtools/server/startup/content-process.sys.mjs b/devtools/server/startup/content-process.sys.mjs
index 59abb3396c8e..d9c93d79f908 100644
--- a/devtools/server/startup/content-process.sys.mjs
+++ b/devtools/server/startup/content-process.sys.mjs
@@ -30,7 +30,9 @@ export function initContentProcessTarget(msg) {
   // using it in the same process.
   const loader = useDistinctSystemPrincipalLoader(loaderRequester);
 
-  const { DevToolsServer } = loader.require("devtools/server/devtools-server");
+  const { DevToolsServer } = loader.require(
+    "resource://devtools/server/devtools-server.js"
+  );
 
   DevToolsServer.init();
   // For browser content toolbox, we do need a regular root actor and all tab
@@ -44,7 +46,7 @@ export function initContentProcessTarget(msg) {
   conn.parentMessageManager = mm;
 
   const { ContentProcessTargetActor } = loader.require(
-    "devtools/server/actors/targets/content-process"
+    "resource://devtools/server/actors/targets/content-process.js"
   );
 
   const actor = new ContentProcessTargetActor(conn, {
diff --git a/devtools/server/startup/worker.js b/devtools/server/startup/worker.js
index ac23bf7cf9be..fb8bfd51d50f 100644
--- a/devtools/server/startup/worker.js
+++ b/devtools/server/startup/worker.js
@@ -48,9 +48,11 @@ this.rpc = function(method, ...params) {
 loadSubScript("resource://devtools/shared/loader/worker-loader.js");
 
 const { WorkerTargetActor } = worker.require(
-  "devtools/server/actors/targets/worker"
+  "resource://devtools/server/actors/targets/worker.js"
+);
+const { DevToolsServer } = worker.require(
+  "resource://devtools/server/devtools-server.js"
 );
-const { DevToolsServer } = worker.require("devtools/server/devtools-server");
 
 DevToolsServer.createRootActor = function() {
   throw new Error("Should never get here!");
diff --git a/devtools/server/tests/xpcshell/head_dbg.js b/devtools/server/tests/xpcshell/head_dbg.js
index 8cb7c12943b3..fb66557563d9 100644
--- a/devtools/server/tests/xpcshell/head_dbg.js
+++ b/devtools/server/tests/xpcshell/head_dbg.js
@@ -41,7 +41,7 @@ const {
   DevToolsServer,
 } = require("resource://devtools/server/devtools-server.js");
 const { DevToolsServer: WorkerDevToolsServer } = worker.require(
-  "devtools/server/devtools-server"
+  "resource://devtools/server/devtools-server.js"
 );
 const {
   DevToolsClient,
diff --git a/devtools/shared/commands/commands-factory.js b/devtools/shared/commands/commands-factory.js
index 1754194ec176..9f7d5fe053c6 100644
--- a/devtools/shared/commands/commands-factory.js
+++ b/devtools/shared/commands/commands-factory.js
@@ -184,7 +184,7 @@ exports.CommandsFactory = {
       freshCompartment: true,
     });
     const { DevToolsServer: customDevToolsServer } = customLoader.require(
-      "devtools/server/devtools-server"
+      "resource://devtools/server/devtools-server.js"
     );
 
     customDevToolsServer.init();
diff --git a/devtools/shared/loader/Loader.jsm b/devtools/shared/loader/Loader.jsm
index ac8408cc4499..e6a596ef2ce2 100644
--- a/devtools/shared/loader/Loader.jsm
+++ b/devtools/shared/loader/Loader.jsm
@@ -139,7 +139,7 @@ function DevToolsLoader({
 
   // Fetch custom pseudo modules and globals
   const { modules, globals } = this.require(
-    "devtools/shared/loader/builtin-modules"
+    "resource://devtools/shared/loader/builtin-modules.js"
   );
 
   // Register custom pseudo modules to the current loader instance
diff --git a/devtools/shared/security/tests/xpcshell/test_devtools_socket_status.js b/devtools/shared/security/tests/xpcshell/test_devtools_socket_status.js
index 82691640c8a6..986d59cb55d8 100644
--- a/devtools/shared/security/tests/xpcshell/test_devtools_socket_status.js
+++ b/devtools/shared/security/tests/xpcshell/test_devtools_socket_status.js
@@ -80,7 +80,9 @@ function checkSocketStatus(expectedExcludeFalse, expectedExcludeTrue) {
 async function setupDevToolsServer({ fromBrowserToolbox }) {
   info("Create a separate loader instance for the DevToolsServer.");
   const loader = new DevToolsLoader();
-  const { DevToolsServer } = loader.require("devtools/server/devtools-server");
+  const { DevToolsServer } = loader.require(
+    "resource://devtools/server/devtools-server.js"
+  );
 
   DevToolsServer.init();
   DevToolsServer.registerAllActors();
diff --git a/devtools/shared/test-helpers/browser_allocation_tracker.js b/devtools/shared/test-helpers/browser_allocation_tracker.js
index ee2818b0a11a..1602ddc3fabc 100644
--- a/devtools/shared/test-helpers/browser_allocation_tracker.js
+++ b/devtools/shared/test-helpers/browser_allocation_tracker.js
@@ -17,7 +17,7 @@ const { allocationTracker } = loader.require(
   "chrome://mochitests/content/browser/devtools/shared/test-helpers/allocation-tracker"
 );
 const TrackedObjects = loader.require(
-  "devtools/shared/test-helpers/tracked-objects.jsm"
+  "resource://devtools/shared/test-helpers/tracked-objects.jsm"
 );
 
 // This test record multiple times complete heap snapshot,
diff --git a/devtools/shared/tests/xpcshell/test_eventemitter_destroy.js b/devtools/shared/tests/xpcshell/test_eventemitter_destroy.js
index b48026059215..b562c1c2e9a0 100644
--- a/devtools/shared/tests/xpcshell/test_eventemitter_destroy.js
+++ b/devtools/shared/tests/xpcshell/test_eventemitter_destroy.js
@@ -16,7 +16,7 @@ add_task(function() {
     const loader = new DevToolsLoader();
 
     const ref = Cu.getWeakReference(
-      loader.require("devtools/shared/event-emitter")
+      loader.require("resource://devtools/shared/event-emitter.js")
     );
 
     loader.destroy();
diff --git a/devtools/shared/tests/xpcshell/test_independent_loaders.js b/devtools/shared/tests/xpcshell/test_independent_loaders.js
index 9cffc723f745..ee8771db255c 100644
--- a/devtools/shared/tests/xpcshell/test_independent_loaders.js
+++ b/devtools/shared/tests/xpcshell/test_independent_loaders.js
@@ -12,8 +12,8 @@ function run_test() {
   const loader1 = new DevToolsLoader();
   const loader2 = new DevToolsLoader();
 
-  const indent1 = loader1.require("devtools/shared/indentation");
-  const indent2 = loader2.require("devtools/shared/indentation");
+  const indent1 = loader1.require("resource://devtools/shared/indentation.js");
+  const indent2 = loader2.require("resource://devtools/shared/indentation.js");
 
   Assert.ok(indent1 !== indent2);
 
diff --git a/devtools/shared/tests/xpcshell/test_invisible_loader.js b/devtools/shared/tests/xpcshell/test_invisible_loader.js
index 81cafb1718c1..0ba41a6b6e43 100644
--- a/devtools/shared/tests/xpcshell/test_invisible_loader.js
+++ b/devtools/shared/tests/xpcshell/test_invisible_loader.js
@@ -21,7 +21,7 @@ function visible_loader() {
   const loader = new DevToolsLoader({
     invisibleToDebugger: false,
   });
-  loader.require("devtools/shared/indentation");
+  loader.require("resource://devtools/shared/indentation.js");
 
   const dbg = new Debugger();
   const sandbox = loader.loader.sharedGlobalSandbox;
@@ -38,7 +38,7 @@ function invisible_loader() {
   const loader = new DevToolsLoader({
     invisibleToDebugger: true,
   });
-  loader.require("devtools/shared/indentation");
+  loader.require("resource://devtools/shared/indentation.js");
 
   const dbg = new Debugger();
   const sandbox = loader.loader.sharedGlobalSandbox;
diff --git a/devtools/shared/tests/xpcshell/test_require_lazy.js b/devtools/shared/tests/xpcshell/test_require_lazy.js
index 61a49f3e5b9d..71316d7d223e 100644
--- a/devtools/shared/tests/xpcshell/test_require_lazy.js
+++ b/devtools/shared/tests/xpcshell/test_require_lazy.js
@@ -25,7 +25,7 @@ function run_test() {
 
   // We have to init the loader by loading any module before
   // lazyRequireGetter is available
-  loader2.require("devtools/shared/DevToolsUtils");
+  loader2.require("resource://devtools/shared/DevToolsUtils.js");
 
   loader2.lazyRequireGetter(o2, name, path);
   Assert.ok(o2.asyncUtils !== asyncUtils);
diff --git a/devtools/startup/DevToolsStartup.sys.mjs b/devtools/startup/DevToolsStartup.sys.mjs
index 9540b522abc0..991d833d0a65 100644
--- a/devtools/startup/DevToolsStartup.sys.mjs
+++ b/devtools/startup/DevToolsStartup.sys.mjs
@@ -994,10 +994,10 @@ DevToolsStartup.prototype = {
       // settings).
       const serverLoader = useDistinctSystemPrincipalLoader(this);
       const { DevToolsServer: devToolsServer } = serverLoader.require(
-        "devtools/server/devtools-server"
+        "resource://devtools/server/devtools-server.js"
       );
       const { SocketListener } = serverLoader.require(
-        "devtools/shared/security/socket"
+        "resource://devtools/shared/security/socket.js"
       );
       devToolsServer.init();