Flutter firebase integration getting error: Failed to turn object into JSON - firebase

Question

All of the sudden I am getting the following error when doing any firebase interaction (auth or firestore) in my flutter Android app.
E/StorageHelpers(15925): Failed to turn object into JSON
E/StorageHelpers(15925): java.lang.NullPointerException: Attempt to invoke virtual method 'org.json.JSONObject com.google.firebase.auth.internal.zzm.zzbf()' on a null object reference
E/StorageHelpers(15925): at com.google.firebase.auth.internal.zzz.zzi(Unknown Source:126)
E/StorageHelpers(15925): at com.google.firebase.auth.internal.zzz.zzg(Unknown Source:3)
E/StorageHelpers(15925): at com.google.firebase.auth.FirebaseAuth.zza(Unknown Source:28)
E/StorageHelpers(15925): at com.google.firebase.auth.zzm.zza(Unknown Source:3)
E/StorageHelpers(15925): at com.google.firebase.auth.api.internal.zzaw.zzaa(Unknown Source:27)
E/StorageHelpers(15925): at com.google.firebase.auth.api.internal.zzcy.zzal(Unknown Source:0)
E/StorageHelpers(15925): at com.google.firebase.auth.api.internal.zzcy.zza(Unknown Source:0)
E/StorageHelpers(15925): at com.google.firebase.auth.api.internal.zzdb.zzb(Unknown Source:42)
E/StorageHelpers(15925): at com.google.firebase.auth.api.internal.zzci.dispatchTransaction(Unknown Source:13)
E/StorageHelpers(15925): at com.google.android.gms.internal.firebase_auth.zzb.onTransact(Unknown Source:22)
E/StorageHelpers(15925): at android.os.Binder.execTransact(Binder.java:697
)
Here are my firebase dependencies:
firebase_auth: "^0.5.3"
cloud_firestore: "^0.7.0+2"
Similar unresolved questions:
https://github.com/invertase/react-native-firebase/issues/1068
Failed to turn object into JSON

Answer 1

I just faced the same problem as yours, I think that's the latest update of Firebase cause this.
In the beginning, I tried to do [Build] > [Clean Project], and [File] > [Invalidate caches/Restart] in Android Studio, but still not working, and this error still occurred.
Finally I fixed this, when I removed the app on my device, and re-install, now everything works fine.
Here's the version I use in my gradle file:
com.google.firebase:firebase-auth:15.1.0
com.google.firebase:firebase-firestore:16.0.0
Hope this can help.