Default FirebaseApp is not initialized in this process. Make sure to call FirebaseApp.initializeApp(Context) first.
i have tried with many things but i am not able to Ge
Upgrade  com.google.gms:google-services to latest version, it will be solved.
Make sure:
AndroidManifest.xml is identical to one in the google-services.jsongoogle-services.json build action is set to GoogleServicesJsonFirebaseApp.InitializeApp(Application.Context); in MainActivity.OnCreate just before the LoadApplication(..) Add the plugin to the build.gradle (app level)
// ADD THIS AT THE BOTTOM
apply plugin: 'com.google.gms.google-services'
For me, none of the solutions worked that were given anywhere. Only this worked. Just had to downgrade my google services from 4.1.0 to 4.0.0
dependencies {
    classpath 'com.android.tools.build:gradle:3.3.0-alpha08'
    classpath 'com.google.gms:google-services:4.0.0'
    /*classpath 'com.google.gms:google-services:4.1.0' <-- this was the problem */
}
So if you have updated the google services, just try to downgrade or change to an older version. Hope it helps