How to handle FirebaseAuthUserCollisionException

Question

I started getting a FirebaseAuthUserCollisionException exception when I try to sign in with Facebook in my Android application

Answer 1

There is no need for this, you can just allow multiple accounts merge under firebaase->authentication-> sign in method -> Advanced - > change (multiple accounts per email address.

Firebase will merge the same email address but will give you different user UID.

See sample below.

AuthCredential authCredential =  FacebookAuthProvider.getCredential(token.getToken());
    
    mAuth.signInWithCredential(authCredential)
            .addOnCompleteListener(this, task -> {
                if (task.isSuccessful()) {
                    // Sign in success, update UI with the signed-in user's information
                    Log.d(TAG, "signInWithCredential:success");
                    FirebaseUser user = mAuth.getCurrentUser();
                    LoginFacebookGoogleActivity.this.updateUI(user);
                } else {
                    // If sign in fails, display a message to the user.
                    Log.w(TAG, "signInWithCredential:failure", task.getException());

                    if(task.getException() instanceof FirebaseAuthUserCollisionException){
                        FirebaseAuthUserCollisionException exception = (FirebaseAuthUserCollisionException) task.getException();

                        //log this bundle into the analytics to analyze which details you want to collect
                        
                    }

                    Toast.makeText(LoginFacebookGoogleActivity.this, "Authentication failed " + task.getException(), Toast.LENGTH_SHORT).show();
                    LoginFacebookGoogleActivity.this.updateUI(null);
                }
            });