How to Troubleshoot Android GCM 401 error?

Question

I\'m getting many 401 Unauthorized errors when trying to connect to Google Cloud Message Server.

Our code was working for some time on

Answer 1

After many checks and not finding a good result the only solution we could give was to create a new project (the 3rd one because we did it already before) with a new API key, and this 3rd time it works.