Hey Mike, sorry to hear you're stuck with this frustrating push notification issue on the Samsung S8+ post-update. Samsung's custom One UI has some unique battery optimization and notification handling quirks that often cause these kinds of problems, even when things work fine on other devices. Let's walk through targeted fixes that have resolved similar cases:

• Check Samsung's Aggressive Battery Optimization
  Samsung's built-in battery tools are notorious for killing background processes, including GCM/FCM listeners. Head to your device's Settings > Battery and Device Maintenance > Battery > Background Limits and make sure your app isn't in the "Deep Sleeping Apps" or "Restricted Apps" lists. Also, enable Allow Background Activity for your app under the same battery settings—this prevents the system from shutting down the push listener when the app is in the background.

• Verify GCM Token Refresh Logic
  App updates can sometimes invalidate existing GCM tokens without triggering a refresh. Double-check your implementation of the onNewToken method: ensure it's correctly updating the token on your backend server, and that your server is using the latest token to send pushes to the S8+. You can add debug logs to confirm the token is being retrieved and sent successfully on the S8+ specifically.

• Adjust Push Notification Priority
  Samsung's notification system often deprioritizes or delays low-priority pushes. Make sure your push payload uses high priority (set priority: high in your FCM/GCM request, or use NotificationCompat.PRIORITY_HIGH when building local notifications). This tells the system to deliver the notification immediately instead of queuing it for later.

• Whitelist Your App in Samsung's Security Tools
  Samsung's Smart Manager or Secure Folder can block notifications even if system settings look correct. Go to Settings > Notifications > Advanced Settings > Notification Access and ensure your app has permission to access notifications. Also, check the Smart Manager's "App Control" section to make sure your app isn't marked as a "battery-draining" app or subject to notification filtering.

• Confirm Post-Update Permissions
  If your update targeted Android 13 or higher, ensure your app has requested and been granted the POST_NOTIFICATIONS runtime permission. Even if the user enabled notifications in settings, missing this permission can block pushes on some Samsung devices. You should also verify that the WAKE_LOCK permission is enabled if your app needs to wake the device for notifications.

• Upgrade to FCM SDK (If Still Using GCM)
  GCM has been deprecated in favor of Firebase Cloud Messaging (FCM), and Samsung's newer One UI versions have better compatibility with FCM. Update your app to use the latest FCM SDK (e.g., com.google.firebase:firebase-messaging:24.0.0+) and re-test—this often resolves compatibility issues with Samsung devices.

If none of these steps work, try capturing a Logcat session on the S8+ while sending a push. Filter logs for tags like FirebaseMessaging, GCM, or your app's package name to look for errors like token retrieval failures, message delivery blocks, or permission denials. That should give you a clearer picture of where the breakdown is happening.

内容的提问来源于stack exchange，提问作者Mike