diff --git a/.changeset/polite-shoes-allow.md b/.changeset/polite-shoes-allow.md
new file mode 100644
index 0000000000..d3c5e34d7a
--- /dev/null
+++ b/.changeset/polite-shoes-allow.md
@@ -0,0 +1,5 @@
+---
+'@backstage/frontend-app-api': patch
+---
+
+Added the ability to ignore unknown extension config.
diff --git a/packages/frontend-app-api/report.api.md b/packages/frontend-app-api/report.api.md
index f24d662df4..661da88210 100644
--- a/packages/frontend-app-api/report.api.md
+++ b/packages/frontend-app-api/report.api.md
@@ -34,6 +34,7 @@ export function createSpecializedApp(options?: {
   extensionFactoryMiddleware?:
     | ExtensionFactoryMiddleware
     | ExtensionFactoryMiddleware[];
+  flags?: SpecializedAppFlags;
 }): {
   apis: ApiHolder;
   tree: AppTree;
@@ -41,4 +42,9 @@ export function createSpecializedApp(options?: {
 
 // @public @deprecated (undocumented)
 export type FrontendFeature = FrontendFeature_2;
+
+// @public (undocumented)
+export type SpecializedAppFlags = {
+  allowUnknownExtensionConfig?: boolean;
+};
 ```
diff --git a/packages/frontend-app-api/src/wiring/createSpecializedApp.tsx b/packages/frontend-app-api/src/wiring/createSpecializedApp.tsx
index 3d356e2a74..e1b7f56227 100644
--- a/packages/frontend-app-api/src/wiring/createSpecializedApp.tsx
+++ b/packages/frontend-app-api/src/wiring/createSpecializedApp.tsx
@@ -74,7 +74,7 @@ import { ApiRegistry } from '../../../core-app-api/src/apis/system/ApiRegistry';
 // eslint-disable-next-line @backstage/no-relative-monorepo-imports
 import { AppIdentityProxy } from '../../../core-app-api/src/apis/implementations/IdentityApi/AppIdentityProxy';
 import { BackstageRouteObject } from '../routing/types';
-import { FrontendFeature, RouteInfo } from './types';
+import { FrontendFeature, RouteInfo, SpecializedAppFlags } from './types';
 import { matchRoutes } from 'react-router-dom';
 
 function deduplicateFeatures(
@@ -208,7 +208,7 @@ export function createSpecializedApp(options?: {
   extensionFactoryMiddleware?:
     | ExtensionFactoryMiddleware
     | ExtensionFactoryMiddleware[];
-  flags?: Record<string, boolean>;
+  flags?: SpecializedAppFlags;
 }): { apis: ApiHolder; tree: AppTree } {
   const config = options?.config ?? new ConfigReader({}, 'empty-config');
   const features = deduplicateFeatures(options?.features ?? []);
diff --git a/packages/frontend-app-api/src/wiring/types.ts b/packages/frontend-app-api/src/wiring/types.ts
index 2bf08f327f..d7af7bd528 100644
--- a/packages/frontend-app-api/src/wiring/types.ts
+++ b/packages/frontend-app-api/src/wiring/types.ts
@@ -28,3 +28,8 @@ export type RouteInfo = {
   routeParents: Map<RouteRef, RouteRef | undefined>;
   routeObjects: BackstageRouteObject[];
 };
+
+/** @public */
+export type SpecializedAppFlags = {
+  allowUnknownExtensionConfig?: boolean;
+};