Firebase Auth: Requests from this Android client application com.xxx are blocked

Question

I\'m implementing the standard tutorial for Firebase AuthUI in my android app. However, when testing I try to sign-in using Google sign-in from within the app and get the follow

Answer 1

The Google Cloud API key I was using was restricted to android with my package name, but only the production SHA-1 certificate fingerprint was given, not the debug key. I added the debug key's SHA-1 certificate along with the package name so that both production and debug certificates appear in the "Application Restrictions" for the key and it worked. Apparently being "blocked" by firebase means your API key may be restricted improperly.