This changes the scenario completely. If you are experiencing the problem only on some devices, it may be due to how the device token is obtained. Let me explain.

As per Google’s suggested practices, if the package version of the app doesn’t change, our Android client library skips requesting a device token and reuses the last one it obtained (which is always saved on the SharedPreferences). So, the error may be due to some of your devices still using a token obtained with the previous sender ID.

If this is the case, uninstalling and reinstalling the app on those devices will force our client library to request a new token and should fix the problem.

Let me know if this is of help.