Irregularity in receiving Firebase notifications

Question

Sometimes even with a valid Firebase token, the notification is not sent to our users. Also often there is a delay when a notification is scheduled to all our users. In many cases this delay is more than 30 min. I have thoroughly checked our logs and there are no error responses when we send requests to FCM

Answer 1

Firebase does not guarantee notification delivery. If you dig deep you will find many reported scenarios where this issue has been reported:

1. Android: Delay in Receiving message in FCM(onMessageReceived)

2. https://github.com/firebase/quickstart-android/issues/83

3. https://github.com/firebase/quickstart-android/issues/83

Main scenarios could be:

• If the internet is not available.
• Differences in devices, how the code is written to handle notifications in different android versions.
• Background / foreground status.