I am trying to add notification services to my app using FCM and tutorial given on https://www.simplifiedcoding.net/firebase-cloud-messaging-android/ Everything has done and
It's an Android Studio bug, it is NOT offering to automatically upgrade firebase libs like it does for play-services* libs.
autoupdate
compile 'com.google.android.gms:play-services-drive:10.0.1'
no autoupdate (need to manually up the version to same as play-services*)
compile 'com.google.firebase:firebase-messaging:10.0.1'