Google Play Game Services sign in button spits “Unknown error”

Question

I\'m trying to use Google Play Game Services in my practice Android app.

I got the sign in buttons UI as explained in the developer guide. When I hit the sign in for the

Answer 1

Try going to your Google+ settings on your device and purging the access that you had granted the app. Afterwards, MANUALLY set up Google+ for your test account, either through a PC/Mac web browser or through your device, then try re-linking the app. This worked for me.

Exact steps for Samsung Galaxy S3:

Settings -> Google -> Google+ -> Apps with Google+ Sign-In -> tap the app and at the bottom, tap Disconnect App.

For what it’s worth, I also tapped the option to “Delete all activity for this app” as well when I deleted it.