Android Runtime error E/AndroidRuntime: FATAL EXCEPTION: main

   java.lang.RuntimeException: Unable to get provider com.google.firebase.provider.FirebaseInitProvider: java.lang.IllegalStateException: Incorrect provider authority in manifest. Most likely due to a missing applicationId variable in application's build.gradle.
   at android.app.ActivityThread.installProvider(ActivityThread.java:5236)
   at android.app.ActivityThread.installContentProviders(ActivityThread.java:4828)
   at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4768)
   at android.app.ActivityThread.access$1600(ActivityThread.java:154)
   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1441)
   at android.os.Handler.dispatchMessage(Handler.java:102)
   at android.os.Looper.loop(Looper.java:152)
   at android.app.ActivityThread.main(ActivityThread.java:5497)
   at java.lang.reflect.Method.invoke(Native Method)
   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.IllegalStateException: Incorrect provider authority in manifest. Most likely due to a missing applicationId variable in application's build.gradle.
   at com.google.firebase.provider.FirebaseInitProvider.zza(Unknown Source)
   at com.google.firebase.provider.FirebaseInitProvider.attachInfo(Unknown Source)
   at android.app.ActivityThread.installProvider(ActivityThread.java:5233)
   at android.app.ActivityThread.installContentProviders(ActivityThread.java:4828) 
   at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4768) 
   at android.app.ActivityThread.access$1600(ActivityThread.java:154) 
   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1441) 
   at android.os.Handler.dispatchMessage(Handler.java:102) 
   at android.os.Looper.loop(Looper.java:152) 
   at android.app.ActivityThread.main(ActivityThread.java:5497) 
   at java.lang.reflect.Method.invoke(Native Method) 
   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 

Add a single line in your build.gradle(yourProject/platforms/android/build.gradle) file 

   below   defaultConfig {

com.your.app <= Replace this with Your app bundle identifier which you can fine in you config.xml file

    defaultConfig {     
     applicationId "com.your.app" //<== Just add this line in you build.gradle file