Fix Outlook AADSTS90023 Sign-In Error with a Custom Domain
Question details
Users need to resolve a continuous sign-in loop or an AADSTS90023 error stating 'msaredir=1 is supported only on the common tenant' after connecting a custom domain.
- Product
- Microsoft 365 Outlook
- Device & OS
- not provided
- Scenario
- Attempting to sign into Outlook using a custom domain connected to a Microsoft 365 account.
- Observed behavior
- Outlook loops continuously during the sign-in process or displays the AADSTS90023 authentication error.
Ensure you have your Microsoft 365 admin credentials handy and verify the exact name of your subscription, as troubleshooting tenant authentication requires administrator access.
Test Web Access in Private Browsing Mode
This helps isolate whether the issue is caused by a corrupted browser cache, outdated session tokens, or a localized app problem.
Authentication loops are often caused by cached credentials conflicting with newly configured custom domains. Testing in a private window bypasses existing cache.
Launch Google Chrome or Microsoft Edge. Press Ctrl+Shift+N (Chrome) or Ctrl+Shift+P (Edge) to open an InPrivate or Incognito window.
Navigate to outlook.office.com in the address bar of your private window.
Enter your custom domain email address and password to check if the AADSTS90023 error still appears.
Contact Microsoft 365 Support for Tenant Issues
If the error occurs on the web even in a private window, the problem likely lies within the Microsoft 365 tenant or Azure Active Directory configuration.
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Frequently Asked Questions
What does the AADSTS90023 error mean in Microsoft 365?
This error typically indicates an authentication issue within Azure Active Directory, often stating that 'msaredir=1 is supported only on the common tenant'. It frequently occurs when a custom domain is improperly configured or syncing incorrectly with the primary tenant.
Can clearing my browser cache fix the Outlook sign-in loop?
Yes, sometimes stale login tokens cause redirection loops. Testing sign-in via an Incognito or InPrivate window helps determine if clearing your regular browser cache will resolve the issue.
Does the AADSTS90023 error affect my existing emails?
No, this error is strictly an authentication and sign-in roadblock. Your actual mailbox data, emails, and contacts remain safely stored on the Microsoft 365 servers and will be accessible once the login issue is resolved.
