Why doesn't my deployed Android app sign into Google Play Services, while my debug app does?

Question

My Android app's login to Google Play Games services seems to fail silently: after choosing the user in the sign-in activity, onActivityResult() receives a resultCode value of 10002. The Android APIs deposit these messages in the logcat:

W/SignInActivity(16216): onSignInFailed()...
W/SignInActivity(16216): Sign in failed during 6
W/SignInActivity(16216): ==> Returning non-OK result: 10002

while Log.w() commands I placed in onActivityResult() deposit these messages:

W/Main activity(16167): In activity result with code 10002
W/Main activity(16167): activity result requests sign in
W/Main activity(16167): unsolved resolution

The strange thing is that it used to work, and when I try to debug it from Android Studio, login works perfectly every time , so I can't even debug the app!

Where can I get started debugging this?

Answer 1

I found the solution thanks to a problem with the same error but a completely different cause , but this situation is different in that it was caused by activating a feature in the Google Play Developer Console.

The keys to this particular error are that:

1. The production app used to work properly, but doesn't any more.
2. The debug version still works properly.

Back in May, Google introduced a feature wherein they sign your app in the Play Store . My original app was signed with the certificate generated by Android Studio, but Google seems pretty gung-ho about their signing so I switched to that without reading the fine print very carefully. As a result:

• For the debug app, the Google Play Games API expected the debug certificate, and Android Studio still used that certificate to generate a debug apk, so the Games API routinely accepted sign-in while debugging.
• For the production app, the API expected the Android Studio-generated production certificate, which Android Studio happily supplied, but Google Play replaced with its own certificate, so the Games API routinely rejected sign-in.

The solution is to:

• stop cursing;
• visit the App signing option under Release management in the usual Play Store developer Console ;
• copy the SHA-1 fingerprint under "App signing certificate" ( not the fingerprint "Upload certificate" -- that's what got you into this mess);
• visit the Credentials page at Google's site for developers
• select your app
• paste the certificate you just copied into the text field labeled "Signing-certificate fingerprint." (The field itself is below some instructions on how to extract it from your keystore -- don't use those instructions when Google signs your app!)

At this point the deployed version worked for me like magic. No programming required!