diff --git a/packages/frontend-app-api/src/tree/resolveAppNodeSpecs.ts b/packages/frontend-app-api/src/tree/resolveAppNodeSpecs.ts
index cf28a80b6a..3da68dcb50 100644
--- a/packages/frontend-app-api/src/tree/resolveAppNodeSpecs.ts
+++ b/packages/frontend-app-api/src/tree/resolveAppNodeSpecs.ts
@@ -33,14 +33,14 @@ export function resolveAppNodeSpecs(options: {
   builtinExtensions?: Extension<any, any>[];
   parameters?: Array<ExtensionParameters>;
   forbidden?: Set<string>;
-  ignoreStaleExtensionConfig?: boolean;
+  allowUnknownExtensionConfig?: boolean;
 }): AppNodeSpec[] {
   const {
     builtinExtensions = [],
     parameters = [],
     forbidden = new Set(),
     features = [],
-    ignoreStaleExtensionConfig = false,
+    allowUnknownExtensionConfig = false,
   } = options;
 
   const plugins = features.filter(OpaqueFrontendPlugin.isType);
@@ -204,7 +204,7 @@ export function resolveAppNodeSpecs(options: {
         existing.params.disabled = Boolean(overrideParam.disabled);
       }
       order.set(extensionId, existing);
-    } else if (!ignoreStaleExtensionConfig) {
+    } else if (!allowUnknownExtensionConfig) {
       throw new Error(`Extension ${extensionId} does not exist`);
     }
   }
diff --git a/packages/frontend-app-api/src/wiring/createSpecializedApp.tsx b/packages/frontend-app-api/src/wiring/createSpecializedApp.tsx
index 011773a1df..3d356e2a74 100644
--- a/packages/frontend-app-api/src/wiring/createSpecializedApp.tsx
+++ b/packages/frontend-app-api/src/wiring/createSpecializedApp.tsx
@@ -208,6 +208,7 @@ export function createSpecializedApp(options?: {
   extensionFactoryMiddleware?:
     | ExtensionFactoryMiddleware
     | ExtensionFactoryMiddleware[];
+  flags?: Record<string, boolean>;
 }): { apis: ApiHolder; tree: AppTree } {
   const config = options?.config ?? new ConfigReader({}, 'empty-config');
   const features = deduplicateFeatures(options?.features ?? []);
@@ -221,9 +222,7 @@ export function createSpecializedApp(options?: {
       ],
       parameters: readAppExtensionsConfig(config),
       forbidden: new Set(['root']),
-      ignoreStaleExtensionConfig: config.getOptionalBoolean(
-        'app.ignoreStaleExtensionConfig',
-      ),
+      allowUnknownExtensionConfig: options?.flags?.allowUnknownExtensionConfig,
     }),
   );