Are your Microsoft 365 apps constantly prompting you to sign in again, even though you’ve already logged in? This frustrating sign-in loop affects Outlook, Word, Excel, PowerPoint, Teams, and other Office 365 applications. This guide explains the root causes and provides every proven fix to stop Office 365 from repeatedly asking for your credentials.
Why Does Office 365 Keep Asking Me to Sign In?
The Microsoft 365 sign-in loop is typically caused by corrupted cached credentials in Windows Credential Manager, an expired authentication token, a conflict between multiple Microsoft accounts on the same device, your organization’s conditional access policies, or Modern Authentication not being properly configured. Sometimes a pending Windows or Office update is the culprit.
Fix 1: Clear Microsoft Credentials from Windows Credential Manager
This is the most effective fix for the Office 365 sign-in loop. Go to Control Panel → Credential Manager → Windows Credentials tab. Look for any entries starting with “MicrosoftOffice,” “Microsoft_OC,” “MS.Teams,” “Office 16,” or any entry containing your email address or “Office.” Select each one and click Remove. After removing all Microsoft-related credentials, restart Office and sign in fresh. Your files and data are not deleted — only the cached login tokens are removed.
Fix 2: Sign Out and Back Into All Office Apps
Open any Office app (like Word or Excel), go to File → Account → Sign out. Do this in every Office application you have open. Then close all Office apps completely. Restart your computer, open one Office app, and sign in fresh with your Microsoft 365 credentials. This forces a new authentication token to be generated.
Fix 3: Update Microsoft 365
Many authentication issues in Office 365 are caused by known bugs that Microsoft has already fixed in updates. In any Office app, go to File → Account → Update Options → Update Now. Wait for the update to complete and restart all Office apps. Running the latest version of Office ensures you have the most current authentication fixes.
Fix 4: Re-Register Office with Your Account
Sometimes Office’s connection to your Microsoft account needs to be re-established. In any Office app, go to File → Account. Under “User Information,” check if your account is listed correctly. If you see multiple accounts, remove all but your primary one. If your license shows any issues, click “Fix Now” or “Activate” and follow the prompts to re-authenticate your Microsoft 365 subscription.
Fix 5: Repair Microsoft Office
A corrupted Office installation can cause persistent authentication failures. Go to Settings → Apps → Installed apps (Windows 11) or Control Panel → Programs and Features (Windows 10). Find Microsoft 365 or Microsoft Office in the list, click it, and select Modify → Quick Repair. If Quick Repair doesn’t fix the issue, try Online Repair — this downloads and replaces all Office files while preserving your settings and data.
Fix 6: Check and Reset Modern Authentication
Modern Authentication (OAuth 2.0) is required for Office 365 to work properly with multi-factor authentication. If it’s disabled or misconfigured, Office will continually prompt for passwords. For IT administrators: verify that Modern Authentication is enabled in the Microsoft 365 admin center under Settings → Org settings → Modern authentication. For end users: check with your IT department that your account is configured for Modern Authentication.
Fix 7: Remove and Re-Add Your Work or School Account
Sometimes Windows needs to forget and re-authenticate your Microsoft 365 work or school account. Go to Settings → Accounts → Access work or school. If you see your work email listed, click it and select Disconnect. Restart your computer, then reconnect by clicking Connect and signing in with your work credentials. This can resolve token refresh issues between Windows and Office.
Fix 8: Check for Conflicting Accounts
If you have both a personal Microsoft account and a work Microsoft 365 account on the same device, they can conflict and cause repeated sign-in prompts. In Office apps (File → Account), ensure only the appropriate account is connected. In Windows Settings → Accounts, review all connected accounts and remove any that aren’t needed. Also check that your default browser is not signed into a different Microsoft account than the one Office uses.
Office 365 Sign-In Loop: Quick Fix Checklist
- Clear Microsoft entries from Windows Credential Manager
- Sign out of all Office apps and sign back in
- Update Microsoft 365 to the latest version
- Run Quick Repair then Online Repair for Office
- Remove work/school account from Windows Settings and re-add
- Check for conflicting Microsoft accounts on the device
- Verify Modern Authentication is enabled (ask your IT admin)
Frequently Asked Questions (FAQ)
Why does Outlook keep asking for my password but Word doesn’t?
Outlook uses separate authentication for email connections (IMAP/Exchange) in addition to the Microsoft account authentication that other Office apps use. If only Outlook is prompting repeatedly, the issue is likely with the email account password stored in Credential Manager for that specific mailbox. Go to Credential Manager and remove any entries containing your email address, then let Outlook re-authenticate.
Will clearing credentials delete my emails or documents?
No. Clearing credentials from Credential Manager only removes the saved authentication tokens (passwords/tokens) — it does not delete any emails, documents, or account data. Your files remain on OneDrive and your emails remain on the server. You’ll just need to sign in again with your username and password.
Still getting the Office 365 sign-in loop? Leave a comment describing which specific app keeps prompting you and whether you’re on a personal or work account — our team will provide targeted troubleshooting steps.