Microsoft 365 Keeps Asking for Your Password in a Loop — How to Fix It

This is a genuinely disruptive issue: Outlook, Word, Excel, or Teams keeps popping up a sign-in prompt, you enter your correct password (sometimes even completing two-factor authentication), and instead of staying signed in, it prompts again shortly after — sometimes in a near-continuous loop that makes the app unusable.

Common causes

• A corrupted or conflicting cached credential. Windows stores cached sign-in tokens, and if one becomes stale or conflicts with a newer one (common after a password change, an account migration, or enrolling in a new security policy), apps can get stuck trying to validate against the wrong cached credential.
• Modern Authentication / token issues. Microsoft 365 uses token-based authentication behind the scenes — if a token expires or becomes invalid in a way the app doesn't properly detect, it can repeatedly attempt and fail to silently refresh it, surfacing as a fresh password prompt each time.
• Multiple accounts signed in simultaneously. Having a personal Microsoft account and a work/school account both signed in within Windows or within an Office app can sometimes create exactly this kind of conflict.
• An organizational Conditional Access policy. If your IT department has security policies requiring specific conditions (managed device, specific network, MFA freshness), and your current session doesn't meet them, this can trigger repeated re-authentication prompts as the system keeps trying and failing to satisfy the policy.

Fix 1: clear cached credentials

1. Press Windows key, type Credential Manager, and open it
2. Click Windows Credentials
3. Look for entries related to Microsoft Office, your specific email address, or anything mentioning MicrosoftAccount or your organization's domain
4. Remove these entries (click the entry, then "Remove")
5. Restart the Office app and sign in fresh

Fix 2: sign out of all accounts and sign back in cleanly

1. In any Office app, go to File → Account
2. Click Sign out for any accounts listed
3. Close the Office app completely
4. Reopen it and sign in fresh with just the one account you need

Fix 3: check for multiple conflicting accounts in Windows itself

1. Go to Settings → Accounts → Email & accounts
2. Review what's listed — if you see both a personal Microsoft account and a work/school account, and you only need one for Office, consider removing the one you don't actively need (or at minimum, make sure you're consistently using the correct one when prompted)

Fix 4: repair the Office installation

If the above doesn't resolve it, a corrupted Office installation itself can sometimes cause authentication-layer glitches:

1. Go to Settings → Apps → Installed apps
2. Find Microsoft 365/Office, click the three dots, select Modify
3. Try Quick Repair first; if the issue persists, run Online Repair

If you're on a managed work account

If you've tried the above and the loop persists, this may be coming from your organization's Conditional Access or security policy rather than a local fix being available. Worth flagging to IT directly — they can check whether your device is fully compliant with current policy requirements (enrolled in Intune, meets minimum OS version, etc.), since a non-compliant device can trigger exactly this kind of repeated re-authentication loop that no amount of local troubleshooting will resolve.