I\'m following the sample code given by Google to integrate Google plus with android. https://github.com/googlesamples/google-services/blob/master/android/signin/app/src/mai
Hey i was having same problem, i think in your case either you have not put your google-services.json file inside your app folder or you are not running your signed apk file if this the case first sign your apk and then paste this apk file in your mobile and from their open it, i mean don't run your app from android studio because what it does is it does not run signed apk file on mobile device. Hope this works :)