diff --git a/backend/main.py b/backend/main.py
index 0b2db2d..4fdbfae 100644
--- a/backend/main.py
+++ b/backend/main.py
@@ -327,7 +327,7 @@ MEDIA_DIR = os.getenv("MEDIA_DIR", "/data/media")
 os.makedirs(MEDIA_DIR, exist_ok=True)
 app.mount("/media", StaticFiles(directory=MEDIA_DIR), name="media")
 
-APP_VER = "773"  # muss mit APP_VER in app.js übereinstimmen
+APP_VER = "774"  # muss mit APP_VER in app.js übereinstimmen
 
 @app.get("/.well-known/assetlinks.json")
 async def assetlinks():
diff --git a/backend/static/index.html b/backend/static/index.html
index 9795931..856efe8 100644
--- a/backend/static/index.html
+++ b/backend/static/index.html
@@ -578,7 +578,7 @@
 <script src="/js/api.js?v=94"></script>
 <script src="/js/ui.js?v=94"></script>
 <script src="/js/app.js?v=94"></script>
-<script src="/js/worlds.js?v=773"></script>
+<script src="/js/worlds.js?v=774"></script>
 
 <!-- Feature-Seiten werden lazy geladen -->
 
diff --git a/backend/static/js/app.js b/backend/static/js/app.js
index c140371..9887ed7 100644
--- a/backend/static/js/app.js
+++ b/backend/static/js/app.js
@@ -3,7 +3,7 @@
    Router, State-Management, Navigation, Initialisierung.
    ============================================================ */
 
-const APP_VER     = '773'; // ← bei jedem Deploy mit Frontend-Änderungen erhöhen
+const APP_VER     = '774'; // ← bei jedem Deploy mit Frontend-Änderungen erhöhen
 const APP_VERSION = '1.5.0'; // ← semantische Version, wird bei make release gesetzt
 const IS_STAGING  = location.hostname === 'staging.banyaro.app';
 // Cache-Bust-Parameter nach Update-Reload sofort entfernen
diff --git a/backend/static/sw.js b/backend/static/sw.js
index 52ca2cf..171d7f4 100644
--- a/backend/static/sw.js
+++ b/backend/static/sw.js
@@ -3,7 +3,7 @@
    Offline-Cache + Push Notifications + Tile-Cache
    ============================================================ */
 
-const CACHE_VERSION = 'by-v773';
+const CACHE_VERSION = 'by-v774';
 const CACHE_STATIC  = `${CACHE_VERSION}-static`;
 const CACHE_TILES   = 'ban-yaro-tiles-v1';  // bleibt über SW-Updates erhalten
 const CACHE_API     = 'ban-yaro-api-v1';    // API-Response-Cache
@@ -292,7 +292,8 @@ self.addEventListener('fetch', event => {
           }
           return response;
         })
-        .catch(() => caches.match(event.request))
+        .catch(() => caches.match(event.request)
+          .then(cached => cached || new Response('', { status: 503 })))
     );
     return;
   }
@@ -324,9 +325,8 @@ self.addEventListener('fetch', event => {
         })
       )
       .catch(() => {
-        if (event.request.mode === 'navigate') {
-          return caches.match('/');
-        }
+        if (event.request.mode === 'navigate') return caches.match('/');
+        return new Response('', { status: 503 });
       })
   );
 });