Troubleshooting GCP OAuth Configuration Issues

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When encountering this error, it usually indicates that the Google OAuth authentication request is misconfigured or lacks the proper permissions. Below are some possible causes and their solutions.

Possible Causes and Solutions

1. Misconfigured OAuth Client Settings

  • Cause: The redirect URI registered in Google Cloud Console does not match the actual request.
  • Solution:
    1. Go to Google Cloud Console.
    2. Navigate to API & Services > Credentials.
    3. Select your OAuth 2.0 Client ID.
    4. Ensure that the Authorized Redirect URIs include https://yourdomain.com/api/v1/admin/auth/google.

2. Incomplete API Authentication Settings

  • Cause: Required APIs may not be enabled for your Google Cloud project.
  • Solution:
    1. Go to API & Services > Enabled APIs & Services.
    2. Ensure that Google Identity Platform and OAuth 2.0 API are enabled.
    3. If necessary, enable them manually.

3. Unregistered Redirect URL

  • Cause: The redirect URL used in the authentication request is not listed in the OAuth client settings.
  • Solution:
    1. Navigate to OAuth Consent Screen settings in Google Cloud Console.
    2. Add yourdomain.com to the Authorized Domains list.
    3. Add the required Redirect URI (e.g., https://yourdomain.com/api/v1/admin/auth/google).

4. Insufficient OAuth Scopes

  • Cause: The request does not include the necessary OAuth scopes for authentication.
  • Solution:
    1. Ensure that the requested scopes include:
      • https://www.googleapis.com/auth/userinfo.email
      • https://www.googleapis.com/auth/userinfo.profile
    2. Verify that the authentication request to https://accounts.google.com/o/oauth2/auth includes these scopes.

5. Client ID Restriction

  • Cause: The authentication request is coming from an unapproved domain.
  • Solution:
    1. Open Google Cloud Console and go to OAuth Client ID settings.
    2. Verify the Application Type (Web, Android, iOS, etc.).
    3. Ensure that the Authorized JavaScript Origins include https://yourdomain.com.

6. Firewall or Access Restrictions

  • Cause: The server cannot reach Google’s authentication servers due to network restrictions.
  • Solution:
    • Check firewall settings to ensure access to accounts.google.com is not blocked.
    • Run curl https://accounts.google.com on your server to verify connectivity.

7. CORS Policy Issues

  • Cause: Cross-Origin Resource Sharing (CORS) settings prevent the authentication request.
  • Solution:
    • Ensure your backend allows requests from https://yourdomain.com.
    • Configure Access-Control-Allow-Origin properly.

🔍 Things to Check

  1. Review OAuth Client Settings in Google Cloud Console.
  2. Enable necessary APIs for OAuth authentication.
  3. Verify that Redirect URIs are correctly configured.
  4. Ensure required scopes are included in the request.
  5. Check server logs for additional error details.