As I was going through some posts on the Internet learning more about signing your Android app, I got post like how to sign the app, and something
All these answers and there is STILL just one missing. When you create your auth credential in the Google API section of the dev console, make sure (especially if it is your first one) that you have clicked on the 'consent screen' option. If you don't have the 'title' and any other required field filled out the call will fail with this option.