Firebase Android: An internal error has occurred. [ OPERATION_NOT_ALLOWED ]

Question

Signing in via Google in my application gives this error:

An internal error has occurred. [ OPERATION_NOT_ALLOWED ]

I have enabl

Answer 1

1. Go to https://console.firebase.google.com/
2. Select your project.
3. Click on Authentication from menu option
4. Click on SIGN-IN-METHOD
5. Click on Google and enable it.

Than it works fine :)