This post is part of a series where I list out errors I've faced during various projects, in the hope that it might help someone, or myself in future.

Below is the error encountered while using "com.firebaseui:firebase-ui-auth:7.2.0" package in my Android app.

This was while trying to sign in to Google account from a unsigned debug application during development.

A sign-in error occurred.
com.firebase.ui.auth.FirebaseUiException: Code: 10, message: 10: 
    at com.firebase.ui.auth.data.remote.GoogleSignInHandler.onActivityResult(GoogleSignInHandler.java:114)
    at com.firebase.ui.auth.ui.idp.SingleSignInActivity.onActivityResult(SingleSignInActivity.java:144)
    at android.app.Activity.dispatchActivityResult(Activity.java:8382)
    at android.app.ActivityThread.deliverResults(ActivityThread.java:5294)
    at android.app.ActivityThread.handleSendResult(ActivityThread.java:5340)
    at android.app.servertransaction.ActivityResultItem.execute(ActivityResultItem.java:54)
    at android.app.servertransaction.ActivityTransactionItem.execute(ActivityTransactionItem.java:45)
    at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
    at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2210)
    at android.os.Handler.dispatchMessage(Handler.java:106)
    at android.os.Looper.loopOnce(Looper.java:201)
    at android.os.Looper.loop(Looper.java:288)
    at android.app.ActivityThread.main(ActivityThread.java:7839)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003)

Resolution

The solution was to use a signed application, the authentication flow from firebaseui.auth package does not work with unsigned applications.

Once I used Android Studio's "Build -> Generate Signed Bundle / APK..." option and installed the app, the auth flow worked fine.