Fix Outlook Sign-In Error CAA2000B

Fix Outlook Sign-In Error CAA2000B

Fix Outlook Sign-In Error CAA2000B

Overview

Error CAA2000B appears when Outlook for Windows cannot complete sign-in with Microsoft 365. The message reads: "The request is not valid for the application's 'userAudience' configuration." It usually means Outlook's stored credentials are out of sync with Microsoft's identity service. This guide walks you through the fixes in order of how often they work.

Before You Begin

  • Outlook for Windows, currently showing the error.
  • Your work email and password.
  • Your phone or Authenticator app for multi-factor authentication.
  • Administrator access on your PC is helpful but not required for most fixes.

Steps

Fix 1: Sign Out of Office and Sign Back In

  1. Open any Office app (Word or Excel).
  2. Click File → Account.
  3. Under User Information, click Sign out.
  4. Close all Office apps, including Outlook and Teams.
  5. Reopen Outlook.
  6. Sign in with your work email when prompted, and approve the multi-factor authentication prompt.

Fix 2: Clear Cached Credentials

  1. Press the Windows key, type Credential Manager, and open it.
  2. Click Windows Credentials.
  3. Find any entries that start with MicrosoftOffice, MS.Outlook, or your work email domain.
  4. Click each entry and click Remove.
  5. Restart your PC.
  6. Open Outlook and sign in again.

Fix 3: Update Office

  1. In any Office app, click File → Account → Update Options → Update Now.
  2. Wait for the update to finish, then restart Outlook.

Fix 4: Create a New Outlook Profile

If the steps above do not work, the profile may be corrupted. See the article Create a New Outlook Profile for the full walkthrough.

Troubleshooting

  • If the error returns after every restart: your computer's clock may be wrong. Right-click the clock, choose Adjust date/time, and turn on Set time automatically.
  • If you cannot remove credentials in Credential Manager: sign out of Windows and back in, then try again.
  • If the error appears only on a new PC: the device may not be properly joined to Microsoft Entra ID. Submit a ticket and we will check enrollment.
  • If nothing works: submit a ticket with a screenshot of the error and the time it last happened.

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Need More Help?

Submit a ticket at support.bostonmit.com or email support@bostonmit.com.

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