Browse all

How to Fix Firebase Auth Invalid Credential Error

Fix Firebase Auth Invalid Credential Error

Why Fixing This Issue Matters

If you’ve been building a Flutter app with Firebase Authentication and decided to integrate Sign in with Apple, chances are you may have come across a frustrating error in your console:

Unhandled Exception: [firebase_auth/invalid-credential] Invalid OAuth response from apple.com

At first glance, this error looks confusing. You might think the problem is with Firebase setup or Apple Developer configuration. However, in reality, it usually comes down to missing parameters in your Apple sign-in implementation.

This issue is more common than you think. Many developers face it, especially after upgrading Flutter or Firebase packages. If you don’t know the exact fix, you could spend hours debugging without progress.

In this guide, we’ll break down:

  • Why the error happens
  • The most common causes behind it
  • Step-by-step solutions with examples
  • Extra tips to prevent it in the future

By the end, you’ll be able to fix the invalid OAuth response error and get your Sign in with Apple + Firebase Auth working smoothly in your Flutter app.

 

Why This Error Happens (Common Causes)

Before we jump into solutions, it’s important to understand why Flutter developers face this error. In simple words, Firebase expects a complete set of credentials from Apple’s authentication process. If even one piece is missing, Firebase will reject the login request and throw the error.

Here are the most common reasons:

  • Missing accessToken in OAuthCredential
    Many tutorials only use idToken and rawNonce, but Apple also requires the authorizationCode as an access token. If you don’t add this, Firebase considers the credential invalid.
  • Outdated Firebase Auth dependency
    If you’re using an older version of firebase_auth, certain parameters like accessToken may not work correctly.
  • Nonce mismatch
    If the rawNonce and nonce values don’t match between Apple’s response and Firebase’s expectation, authentication fails.
  • Apple Developer configuration issues
    • Incorrectly set up Sign in with Apple in the developer console
    • Bundle Identifier mismatch
    • Services ID not linked properly
  • Flutter plugin issues
    Using older versions of sign_in_with_apple or conflicting packages can also cause this error.

 

Step-by-Step Guide to Fix Firebase Auth Invalid Credential Error

Now let’s go through the exact step-by-step solution to fix the [firebase_auth/invalid-credential] Invalid OAuth response from apple.com error in Flutter.

1. Add Sign in with Apple and Request Credentials

Make sure you’re using the latest version of sign_in_with_apple package. Import it and request Apple ID credentials:

final appleCredential = await SignInWithApple.getAppleIDCredential(
  scopes: [
    AppleIDAuthorizationScopes.email,
    AppleIDAuthorizationScopes.fullName,
  ],
  nonce: nonce,
);

Here we request email and full name along with the nonce.

2. Create OAuthCredential with All Required Parameters

This is the most important step. Most errors happen because developers forget to pass the accessToken.

Correct implementation:

final oauthCredential = OAuthProvider("apple.com").credential(
  idToken: appleCredential.identityToken,
  rawNonce: rawNonce,
  accessToken: appleCredential.authorizationCode, // ✅ This line is mandatory
);

Without accessToken, Firebase won’t accept the login request.

3. Sign in with Firebase

Once you have the oauthCredential, simply sign in using Firebase:

final userCredential = await FirebaseAuth.instance.signInWithCredential(oauthCredential);

If everything is set up correctly, the error should disappear and the user will be signed in successfully.

4. Update Firebase Auth Dependency

In your pubspec.yaml, ensure you’re using the latest version of Firebase Auth. Older versions may not support the required parameters properly.

dependencies:
  firebase_auth: ^5.2.0
  sign_in_with_apple: ^6.1.0

Run:

flutter pub get

5. Double-Check Apple Developer Console

  • Go to Apple Developer Console
  • Make sure:
    • Bundle ID matches your Flutter app
    • Sign in with Apple is enabled for your app
    • Services ID is properly linked
    • Key & identifier are added in Firebase project

 

Comparison Table: Missing vs Correct Implementation

Implementation Example Code Result
❌ Missing accessToken OAuthProvider("apple.com").credential(idToken: appleCredential.identityToken, rawNonce: rawNonce) Throws [firebase_auth/invalid-credential] error
✅ Correct implementation OAuthProvider("apple.com").credential(idToken: appleCredential.identityToken, rawNonce: rawNonce, accessToken: appleCredential.authorizationCode) Works correctly, no error

 

Extra Tips to Prevent the Error

Here are some best practices you should follow to ensure your Apple Sign in with Firebase keeps working smoothly:

1. Always Use Latest Packages

  • Update firebase_auth and sign_in_with_apple frequently.
  • Check the FlutterFire documentation for the latest recommended versions.

2. Debug Nonce Carefully

  • If you’re using SHA256 hashing for nonce, make sure the rawNonce you pass is the same one you use when requesting credentials.
  • Mismatched nonces are one of the biggest hidden causes of this error.

3. Enable Associated Domains in Xcode

  • Open your iOS project in Xcode → Select project → Capabilities → Enable Sign in with Apple and Associated Domains.
  • Missing this step can lead to silent failures.

4. Test on Real Devices

  • Sign in with Apple sometimes behaves differently on simulators vs real iPhones.
  • Always test on at least one real iOS device to confirm the fix.

5. Clean & Rebuild Flutter Project

Sometimes cached builds can carry old settings. Run these commands:

flutter clean
flutter pub get

Alternative Workarounds

If the standard fix doesn’t work, here are a few alternatives:

1. Use Firebase Custom Authentication

Instead of directly using Firebase’s Apple provider, you can use Apple’s identity token and then create a custom Firebase token via your backend.

  • This gives you more control over credentials.
  • It’s slightly more complex but avoids some Firebase plugin issues.

2. Try Sign in with Apple JS (Fallback for Web)

If your app is also running on Flutter Web, consider using Apple’s JS SDK for web sign-in and then pass the token to Firebase.

Reference: Apple Sign in JS Guide

3. Downgrade / Upgrade Package Versions

Some developers reported success by switching versions:

  • If the latest Firebase Auth breaks your build, try a stable version like ^5.0.0.
  • Always test both downgrade and upgrade options.

 

FAQs: Fixing Firebase Auth Invalid Credential Error

Here are some common questions developers ask when they face this issue:

1. Why do I get invalid-credential error when signing in with Apple in Flutter?

Because Firebase requires idToken, rawNonce, and accessToken from Apple. If even one is missing, Firebase rejects the credential.

2. Do I need to add accessToken in Apple sign-in for Flutter Firebase?

Yes . Without accessToken (authorizationCode), you’ll see the [firebase_auth/invalid-credential] Invalid OAuth response from apple.com error.

3. How do I update Firebase Auth in Flutter?

Open pubspec.yaml and set:

dependencies:
  firebase_auth: ^5.2.0

Then run flutter pub get.

4. Does this error happen only on iOS?

Mostly yes. Since this error is related to Apple’s OAuth flow, you’ll face it on iOS devices. However, incorrect setup may also affect multi-platform sign-ins.

5. Do I need to configure Apple Sign in in Firebase Console?

No. You only need to configure Apple Sign in on Apple Developer Console and ensure your bundle ID and associated domains match your app setup.

 

Complete Example Code

Here’s a ready-to-use implementation that fixes the error:

import 'package:firebase_auth/firebase_auth.dart';
import 'package:sign_in_with_apple/sign_in_with_apple.dart';

Future<UserCredential> signInWithApple() async {
  final rawNonce = generateNonce();
  final nonce = sha256ofString(rawNonce);

  final appleCredential = await SignInWithApple.getAppleIDCredential(
    scopes: [
      AppleIDAuthorizationScopes.email,
      AppleIDAuthorizationScopes.fullName,
    ],
    nonce: nonce,
  );

  final oauthCredential = OAuthProvider("apple.com").credential(
    idToken: appleCredential.identityToken,
    rawNonce: rawNonce,
    accessToken: appleCredential.authorizationCode, // Important!
  );

  return await FirebaseAuth.instance.signInWithCredential(oauthCredential);
}

Replace generateNonce() and sha256ofString() with your nonce utility functions.

 

SEO Comparison Table: Firebase Auth Versions

Firebase Auth Version Sign in with Apple Support Error Likelihood
v4.x Limited, some missing params High ❌
v5.0.0 Stable, supports idToken + rawNonce Medium ⚠️
v5.2.0+ Full support including accessToken Low ✅

 

Conclusion

Fixing the Firebase Auth invalid-credential error for Apple sign-in in Flutter comes down to understanding what credentials Apple returns and what Firebase expects.

The single most important fix is:

Add the accessToken: appleCredential.authorizationCode when creating your OAuthCredential.

Along with:

  • Keeping firebase_auth up to date
  • Double-checking nonce values
  • Configuring Apple Developer settings correctly

By following this guide, you’ll not only fix the error but also make your Flutter + Firebase app’s Apple Sign in more stable.

Start by updating your code today and test it on a real iOS device. check more blogs from rankweb3

 

 

#Flutter #FirebaseAuth #SignInWithApple #MobileDevelopment #iOSFlutter #OAuth #Firebase

Checkout Below Links for Further Information

Leave a Reply

Your email address will not be published. Required fields are marked *