i wanna add this error too that i saw in logcat but i don't how important it is:
07-26 12:54:50.491 21415-22601/com.moodle.moodlemobile E/AndroidRuntime: FATAL EXCEPTION: pool-2-thread-3
Process: com.moodle.moodlemobile, PID: 21415
java.lang.IllegalAccessError: Method 'void android.support.v4.content.ContextCompat.<init>()' is inaccessible to class 'com.google.android.gms.iid.zzd' (declaration of 'com.google.android.gms.iid.zzd' appears in /data/app/com.moodle.moodlemobile-1/base.apk)
Process: com.moodle.moodlemobile, PID: 21415
java.lang.IllegalAccessError: Method 'void android.support.v4.content.ContextCompat.<init>()' is inaccessible to class 'com.google.android.gms.iid.zzd' (declaration of 'com.google.android.gms.iid.zzd' appears in /data/app/com.moodle.moodlemobile-1/base.apk)