Authentication using Facebook at first and then Google causes an error in Firebase for Android

Question

As I understand from the Firebase Docs, if a user authenticates his account with a credential, he should strictly login by using the same credential if the credential is not

Answer 1

Please check the thread: https://groups.google.com/forum/#!searchin/firebase-talk/liu/firebase-talk/ms_NVQem_Cw/8g7BFk1IAAAJ It explains why this happens. This is due to some security issue with Google emails being verified whereas Facebook emails are not.