Fix Microsoft 365 Sign-In Problems on Mac: Word Signs Out & Excel Crashes
Question details
The user is unable to maintain a stable sign-in session for Microsoft 365 on a Mac, causing Word to request authentication constantly and Excel to crash with a blank sign-in window.
- Product
- Microsoft 365 (Word and Excel for Mac)
- Device & OS
- macOS
- Scenario
- Attempting to open, edit, or save documents in Microsoft Word and Excel using an active Microsoft 365 Family subscription.
- Observed behavior
- Word repeatedly prompts for first-run setup and authentication upon reopening. Excel displays a blank white pop-up window with a spinning gear instead of a login screen, shows activation warnings, and eventually crashes.
Before troubleshooting, ensure your Mac has a stable internet connection and temporarily disable any VPNs, proxies, or strict firewall settings that might block Microsoft's authentication servers.
Clear Keychain Access and Use the Office License Removal Tool
Clear corrupted cached credentials from macOS Keychain and completely remove broken Office licenses to force a clean sign-in.
Authentication loops on macOS are frequently caused by corrupted token data inside the Keychain. Deleting these entries alongside a complete license reset usually resolves both the Word sign-out loop and the Excel blank window crash.
Note: Newer versions of Office use MSAL or OneAuth instead of ADAL, which is why you may not find ADAL entries in your Keychain.
Sign out of all Microsoft Office applications and close them completely using Command + Q.
Open Finder, navigate to Applications > Utilities, and launch the 'Keychain Access' app.
Search for and delete any entries containing 'Microsoft', 'Office', 'MSAL', or 'OneAuth'. Do not delete items unrelated to Microsoft.
Download and run the official Microsoft Office License Removal Tool for Mac. Follow the on-screen prompts to clear previous license files.
Restart your Mac, open Microsoft Word, and sign in again with the Gmail address associated with your Microsoft 365 subscription.
Update macOS, Office, and Verify Network Settings
Outdated software or network interference can prevent Excel from loading its web-based sign-in window.
Use WPS Office as a Stable Alternative on Mac
If Microsoft 365 continues to experience sign-in loops or Excel crashes on your Mac, consider switching to WPS Office. It provides a lightweight, highly compatible, and free alternative without the recurring subscription and complex licensing errors.
Frequently Asked Questions
Why does Microsoft Word repeatedly ask me to sign in on my Mac?
This usually happens when the authentication tokens stored in your Mac's Keychain Access become corrupted or expired. Clearing the Microsoft-related entries in Keychain and signing in again will generate fresh, working credentials.
Why does Excel show a blank white screen with a spinning gear when I try to log in?
The blank login window is often caused by an outdated Office build, network restrictions (like a VPN), or macOS network settings blocking the Microsoft sign-in page from loading properly in Excel's embedded web view.
What does ADAL mean in Mac Keychain Access, and why can't I find it?
ADAL stands for Active Directory Authentication Library. Newer versions of Microsoft Office for Mac have transitioned to MSAL (Microsoft Authentication Library) or OneAuth, which is why you may no longer see ADAL entries in your Keychain Access. You should look for 'MSAL' or 'OneAuth' instead.
