Deleting android app from Firebase problem

Question

I faced a problem that my app can't connect to firebase any more I just deleted my app from firebase project and added it to another project, after that my application can't connect to firebase and I have this message loading

Checking if the app has communicated with our servers. You may need to uninstall and reinstall your app.

and when I try to send FCM notification it not send I have this error message

"error": "MismatchSenderId"

Answer 1

Your app must communicate first with your Firebase project before you start sending any FCM notifications and start using other services.

I recommend you to read this documentation: https://firebase.google.com/docs/android/setup?authuser=0

Make sure that you enter the package name that your app is actually using. You cannot add or modify this value after you register your app with your Firebase project.

And please make sure that you deleted old google-services.json file from your app directory and replaced it with the new one. You can find documentation on this here: https://support.google.com/firebase/answer/7015592?authuser=0

After all these changes, it is recommended that you uninstall your app from the emulator/physical device first, then install it again. Open it a few times, wait for a few minutes and the app should be connected to your firebase project.

Answer 2

I had the exact problem. Google JSON was fine, had uninstalled the app and updated the fcm server key but it didn't work. In the end, all I did was to:

-uninstall the app again

-restart my device

-clean project

-invalidate caches and restart

and it started working.