Circular reference error in firebase with R8

Question

We are getting following error with Firebase and R8.

[CIRCULAR REFERENCE:java.lang.IllegalArgumentException: java.lang.IllegalArgumentException: Multiple entries with same key: Method com.google.firebase.iid.FirebaseInstanceId.zza Proto LLL com.google.android.gms.tasks.Task java.lang.String java.lang.String=Encoded method Method com.google.firebase.iid.FirebaseInstanceId.zza Proto LLL com.google.android.gms.tasks.Task java.lang.String java.lang.String and Method com.google.firebase.iid.FirebaseInstanceId.zza Proto LLL com.google.android.gms.tasks.Task java.lang.String java.lang.String=Encoded method Method com.google.firebase.iid.FirebaseInstanceId.zza Proto LLL com.google.android.gms.tasks.Task java.lang.String java.lang.String]

Please help me with any further pointers to debug this. Let me know if more logs are required to debug this.

EDIT: Its fixed 3.4.0-beta02 onwards.

Answer 1

I've had this error as well in the latest Android Studio 3.5. Fixed it by following the links to the Google Issue Tracker, and by just adding this line in my Proguard rules :

-keep class com.google.firebase.iid.FirebaseInstanceId { zza(...); }