Why Does Firebase Hosting Show a 'Deploy Complete' Screen Instead of My Flutter Web App on Subsequent Deploys?

It sounds like the issue is related to updating the cached assets (especially the service worker) from your previous Flutter web build. This is a common challenge when subsequent deploys don’t seem to update on the client side, even though Firebase shows a successful deploy.

Below are some steps to try:

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1. Update or Bypass the Flutter Service Worker

Flutter’s default web build generates a service worker (flutter_service_worker.js) that caches assets for offline use. If this service worker doesn’t update correctly, your clients might be served a stale or blank version of your application.

Solution options:

• Force a no-cache header for the service worker. You can add a specific header rule in your firebase.json to tell browsers not to cache the service worker file. For example:

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{
  "hosting": {
    "public": "build/web",
    "ignore": [
      "firebase.json",
      "**/.*",
      "**/node_modules/**"
    ],
    "headers": [
      {
        "source": "/flutter_service_worker.js",
        "headers": [
          {
            "key": "Cache-Control",
            "value": "no-cache"
          }
        ]
      }
    ],
    "rewrites": [
      {
        "source": "**",
        "destination": "/index.html"
      }
    ]
  }
}

• Manually update or remove the service worker if you do not want offline caching. (Keep in mind that removing the service worker may affect offline capabilities.)

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2. Do a Hard Refresh or Clear Service Worker Data

Sometimes your browser is still holding on to the old service worker cache. Try these steps on your testing machine:

• Open Developer Tools (usually F12 or Ctrl+Shift+I).
• Go to the Application tab (in Chrome) and under Service Workers, click “Update” or unregister the service worker.
• Do a hard refresh (Ctrl+Shift+R) to force fetching the newest assets.

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3. Clear and Rebuild the Flutter App

Before deploying again, make sure to run a clean build:

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flutter clean
flutter build web

This ensures that no old build artifacts remain.

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4. Verify the Deployment

After deploying with:

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firebase deploy --only hosting

• Open the developer console in your browser.
• Check the Network tab to see if the latest versions of your files are being served.
• Confirm that the flutter_service_worker.js file isn’t being loaded from cache (it should respect the “no-cache” header if you added it).

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By forcing the service worker to not cache (or by unregistering it during development), you should see the updates deployed to Firebase. In production, if you want to keep offline support, consider versioning your assets or updating the service worker registration logic so clients fetch the new version when available.