diff --git a/framework/core/js/src/common/Application.tsx b/framework/core/js/src/common/Application.tsx
index fe74c37b4d..4db332ce34 100644
--- a/framework/core/js/src/common/Application.tsx
+++ b/framework/core/js/src/common/Application.tsx
@@ -279,6 +279,13 @@ export default class Application {
 
   initialRoute!: string;
 
+  /**
+   * @internal
+   */
+  public currentInitializerExtension: string | null = null;
+
+  private handledErrors: { extension: null | string; errorId: string; error: any }[] = [];
+
   public load(payload: Application['data']) {
     this.data = payload;
     this.translator.setLocale(payload.locale);
@@ -288,17 +295,19 @@ export default class Application {
     const caughtInitializationErrors: CallableFunction[] = [];
 
     this.initializers.toArray().forEach((initializer) => {
+      this.currentInitializerExtension = initializer.itemName.includes('/')
+        ? initializer.itemName.replace(/(\/flarum-ext-)|(\/flarum-)/g, '-')
+        : initializer.itemName;
+
       try {
         initializer(this);
       } catch (e) {
-        const extension = initializer.itemName.includes('/')
-          ? initializer.itemName.replace(/(\/flarum-ext-)|(\/flarum-)/g, '-')
-          : initializer.itemName;
-
         caughtInitializationErrors.push(() =>
           fireApplicationError(
-            extractText(app.translator.trans('core.lib.error.extension_initialiation_failed_message', { extension })),
-            `${extension} failed to initialize`,
+            extractText(
+              app.translator.trans('core.lib.error.extension_initialiation_failed_message', { extension: this.currentInitializerExtension })
+            ),
+            `${this.currentInitializerExtension} failed to initialize`,
             e
           )
         );
@@ -727,4 +736,12 @@ export default class Application {
 
     return prefix + url + (queryString ? '?' + queryString : '');
   }
+
+  public handleErrorOnce(extension: null | string, errorId: string, userTitle: string, consoleTitle: string, error: any) {
+    if (this.handledErrors.some((e) => e.errorId === errorId)) return;
+
+    this.handledErrors.push({ extension, errorId, error });
+
+    fireApplicationError(userTitle, consoleTitle, error);
+  }
 }
diff --git a/framework/core/js/src/common/extend.ts b/framework/core/js/src/common/extend.ts
index 4bb3853a69..6ee151d91a 100644
--- a/framework/core/js/src/common/extend.ts
+++ b/framework/core/js/src/common/extend.ts
@@ -1,3 +1,6 @@
+import extractText from './utils/extractText';
+import app from './app';
+
 /**
  * Extend an object's method by running its output through a mutating callback
  * every time it is called.
@@ -28,6 +31,8 @@ export function extend<T extends Record<string, any>, K extends KeyOfType<T, Fun
   methods: K | K[],
   callback: (this: T, val: ReturnType<T[K]>, ...args: Parameters<T[K]>) => void
 ) {
+  const extension = app.currentInitializerExtension;
+
   // A lazy loaded module, only apply the function after the module is loaded.
   if (typeof object === 'string') {
     let [namespace, id] = flarum.reg.namespaceAndIdFromPath(object);
@@ -45,7 +50,17 @@ export function extend<T extends Record<string, any>, K extends KeyOfType<T, Fun
     object[method] = function (this: T, ...args: Parameters<T[K]>) {
       const value = original ? original.apply(this, args) : undefined;
 
-      callback.apply(this, [value, ...args]);
+      try {
+        callback.apply(this, [value, ...args]);
+      } catch (e) {
+        app.handleErrorOnce(
+          extension,
+          `${extension}::extend::${object.constructor.name}::${method.toString()}`,
+          extractText(app.translator.trans('core.lib.error.extension_runtime_failed_message', { extension })),
+          `${extension} failed to extend ${object.constructor.name}::${method.toString()}`,
+          e
+        );
+      }
 
       return value;
     } as T[K];
@@ -86,6 +101,8 @@ export function override<T extends Record<any, any>, K extends KeyOfType<T, Func
   methods: K | K[],
   newMethod: (this: T, orig: T[K], ...args: Parameters<T[K]>) => void
 ) {
+  const extension = app.currentInitializerExtension;
+
   // A lazy loaded module, only apply the function after the module is loaded.
   if (typeof object === 'string') {
     let [namespace, id] = flarum.reg.namespaceAndIdFromPath(object);
@@ -101,7 +118,17 @@ export function override<T extends Record<any, any>, K extends KeyOfType<T, Func
     const original: Function = object[method];
 
     object[method] = function (this: T, ...args: Parameters<T[K]>) {
-      return newMethod.apply(this, [original?.bind(this), ...args]);
+      try {
+        return newMethod.apply(this, [original?.bind(this), ...args]);
+      } catch (e) {
+        app.handleErrorOnce(
+          extension,
+          `${extension}::extend::${object.constructor.name}::${method.toString()}`,
+          extractText(app.translator.trans('core.lib.error.extension_runtime_failed_message', { extension })),
+          `${extension} failed to override ${object.constructor.name}::${method.toString()}`,
+          e
+        );
+      }
     } as T[K];
 
     Object.assign(object[method], original);
diff --git a/framework/core/js/src/common/helpers/fireApplicationError.ts b/framework/core/js/src/common/helpers/fireApplicationError.ts
index b4e8c9e85e..7b6651bcd1 100644
--- a/framework/core/js/src/common/helpers/fireApplicationError.ts
+++ b/framework/core/js/src/common/helpers/fireApplicationError.ts
@@ -3,9 +3,9 @@ import app from '../app';
 /**
  * Fire a Flarum error which is shown in the JS console for everyone and in an alert for the admin.
  *
- * @param userTitle: a user friendly title of the error, should be localized.
- * @param consoleTitle: an error title that goes in the console, doesn't have to be localized.
- * @param error: the error.
+ * @param userTitle a user friendly title of the error, should be localized.
+ * @param consoleTitle an error title that goes in the console, doesn't have to be localized.
+ * @param error the error.
  */
 export default function fireApplicationError(userTitle: string, consoleTitle: string, error: any) {
   console.group(`%c${consoleTitle}`, 'background-color: #d83e3e; color: #ffffff; font-weight: bold;');
diff --git a/framework/core/locale/core.yml b/framework/core/locale/core.yml
index a401e9bff9..3286204230 100644
--- a/framework/core/locale/core.yml
+++ b/framework/core/locale/core.yml
@@ -722,6 +722,7 @@ core:
       db_error_message: "Database query failed. This may be caused by an incompatibility between an extension and your database driver."
       dependent_extensions_message: "Cannot disable {extension} until the following dependent extensions are disabled: {extensions}"
       extension_initialiation_failed_message: "{extension} failed to initialize, check the browser console for further information."
+      extension_runtime_failed_message: "{extension} encountered an error while running. Check the browser console for further information."
       generic_message: "Oops! Something went wrong. Please reload the page and try again."
       generic_cross_origin_message: "Oops! Something went wrong during a cross-origin request. Please reload the page and try again."
       missing_dependencies_message: "Cannot enable {extension} until the following dependencies are enabled: {extensions}"