Repository navigation
[firebase_auth_web] Uncaught TypeError after showing INVALID_LOGIN_CREDENTIALS error (web_utils.dart getFirebaseAuthException) #18680
Description
Description
On Flutter Web, signing in with an incorrect password correctly shows the app's own "wrong password" error dialog, but immediately afterward an uncaught TypeError is thrown from firebase_auth_web's web_utils.dart, during getFirebaseAuthException's conversion of the legacy INVALID_LOGIN_CREDENTIALS error shape returned by the JS SDK.
Our app-side Dart code path is clean: it receives the exception, shows the correct error dialog, and returns null. The uncaught TypeError originates entirely inside firebase_auth_web's JS-interop error conversion, not in our code.
Steps to reproduce
- On Flutter Web, call
FirebaseAuth.instance.signInWithEmailAndPasswordwith a valid email and an incorrect password. - The correct "wrong password" error dialog displays.
- Immediately afterward, an uncaught
TypeErroris thrown in the browser console, originating fromweb_utils.dart'sgetFirebaseAuthException.
Expected behavior
No uncaught exception after the SDK returns the legacy INVALID_LOGIN_CREDENTIALS shape.
Versions
- firebase_auth_web: 6.2.7 (newest at time of filing)
- firebase_core_web: 3.11.0 (newest at time of filing)
- Flutter: 3.47.2
Confirmed still reproducing on the newest releases as of 2026-09-08 (the 3.11.0 core_web fix was scoped to FirebaseCoreWeb.app(), unrelated to this path).
Impact
Cosmetic in our testing (no functional breakage), but it's an uncaught exception that pollutes crash/error monitoring.
Activity
SelaseKay commentedon Sep 11, 2026
Hi @birchdigital, thanks for the report. I'm looking into this.
SelaseKay commentedon Sep 11, 2026
Hi @birchdigital, I’m unable to reproduce this issue using the latest
firebase_authversion (6.6.1). Could you please provide a minimal reproducible example (ideally a repository that isolates the issue and that I can clone), along with clear steps to reproduce the behavior?tamirh commentedon Sep 11, 2026
Hi @SelaseKay we're hitting a similar issue as @birchdigital
On a Flutter web client w/
firebase_auth 6.6.1firebase_auth_web 6.2.7firebase_core_web 3.11.0JS SDK 12.18.0I'm unsure of the root cause, but when
customDatais missing on the exception object, the SDK will throw with:TypeError: null: type 'minified:<tag> is not a subtype of type 'JSObject'This comes from
getFirebaseAuthExceptioninfirebase_auth_web: ``final customData = exception.customData as auth_interop.AuthErrorCustomData;`fix(auth,web): convert Auth errors that omit customData without throw…