diff --git a/frontend/sw-update.js b/frontend/sw-update.js
index d40de07..5853665 100644
--- a/frontend/sw-update.js
+++ b/frontend/sw-update.js
@@ -161,6 +161,9 @@
       const reg = root.navigator && await root.navigator.serviceWorker.getRegistration();
       const worker = reg && (reg.waiting || reg.active);
       const status = await askCacheStatus(worker);
+      // Unknown protocol is a retryable failure, never an empty successful
+      // legacy refresh followed by a reload into the old persistent manifest.
+      if (worker && !status) throw new Error('Worker update status unavailable; try again');
       if (status && status.assetSync) {
         const result = await core.syncAssets(m,{cache,fetchFn:opts.fetchFn});
         if (!reg.waiting) await core.commit(m,cache);
diff --git a/frontend/sw-update.test.js b/frontend/sw-update.test.js
index 7bb6f6e..6ea1ce1 100644
--- a/frontend/sw-update.test.js
+++ b/frontend/sw-update.test.js
@@ -362,3 +362,9 @@ test('explicit playback override clears the worker guard and reloads once',async
  assert.deepStrictEqual(messages,[{type:'PLAYING',value:false},{type:'SKIP_WAITING'}]);
  container.fireControllerChange();container.fireControllerChange();assert.equal(reloads,1);
 });
+test('an unanswered worker status cannot fall through to an empty legacy refresh',async()=>{
+ const vm=require('node:vm'),fs=require('node:fs');
+ const sandbox={AssetSyncCore:{CACHE:'ytplayer-assets'},navigator:{serviceWorker:{getRegistration:async()=>({active:{postMessage(){}}})}}};
+ vm.runInNewContext(fs.readFileSync(__dirname+'/sw-update.js','utf8'),sandbox);
+ await assert.rejects(sandbox.SwUpdate.refreshShellInPlace({cachesApi:{open:async()=>({}),keys:async()=>[]},fetchFn:async()=>({ok:true,json:async()=>({buildTag:'new'})}),isShellCache:()=>true}),/Worker update status unavailable/);
+});