Android app not working after published to Play Store

Question

How can I fix firebase authentication error? I generated a release APK of my app and it works fine on devices users can login as they should.

Then the problem occurs when I have published the very same working APK on the play store and I install from there (playstore). I get the error that

the app is not authorised to use firebase Authentication. please verify that the package name and SHA1 are configured in the firebase console

Answer 1

I fixed it after hours of a headache.

When you publish your apk to the play store, you get assigned with a singing certificate SHA1. That you have to add to your firebase console.