Unable to login in office 365 on Macbook Air

To troubleshoot the "Unknown Error" (error code: 0x0) when signing in to Microsoft applications on your MacBook Air, you can try the following steps:

1. Check Your Internet Connection: Ensure that you have a stable internet connection.
2. Update Microsoft 365: Make sure your Microsoft 365 apps are up to date. Open any Microsoft 365 app (like Word), go to File > Account, and select Update Options > Update Now.
3. Sign Out and Sign Back In: Open a Microsoft 365 app, click on your name or profile picture, select Sign out, and then sign back in with your Work or School account.
4. Remove Office License Files: If the issue persists, you may need to remove Office license files on your Mac. You can find instructions on how to do this in the Microsoft support documentation.
5. Run the Microsoft 365 Sign-in Troubleshooter: Use the Microsoft 365 sign-in troubleshooter to help resolve sign-in issues. You can find it in the Get Help app.
6. Contact Support: If none of the above steps work, consider contacting Microsoft support for further assistance.

These steps should help you resolve the sign-in issue you're experiencing.

References:

• Microsoft 365 Apps activation error: "There's a problem with your account"
• Microsoft 365 Apps activation error: "The products we found in your account can't be used to activate"

Hi, Arun Gandhi

Welcome to Microsoft Q&A forum.

Sorry for this frustrating situation that you're encountering. Here are some workarounds you can try to resolve this issue:

Fix Word sign‑in/activation on macOS (Office for Mac)

• Quit all Office apps (Word, Excel, PowerPoint, Outlook, OneNote). Then restart your Mac and try signing in again in Word. This clears transient auth sessions and cached tokens.

Restore Office’s access to macOS Keychain

• Open Keychain Access.
• In the left pane, select login. From the File menu, choose Lock Keychain “login”.
• Launch Word. When prompted to allow keychain access, enter your Mac admin password and choose OK/Always Allow.
• Sign in when Word asks. Quit and reopen Word to confirm prompts no longer appear.

Remove stale Office licenses/credentials (safe reset)

• Quit all Office apps.
• Run Microsoft’s License Removal Tool to clear old Office keychain entries.
• Open Word and sign in/activate again. This is the fastest way to fix corrupted activation data.

If you installed Office from the Mac App Store, re‑validate the purchase

• Check your Apple Subscriptions to confirm Microsoft 365 is active.
• In Word, choose Restore Purchases (or follow “Restore previous purchase for Office for Mac”).
• Try again after 30–60 minutes if you hit server errors.

Confirm you’re using the correct account (the one tied to the paid Microsoft 365 subscription). If Word shows repeated sign‑in failures, ensure you’re not trying to activate with a different or retired SKU (e.g., Office 2016/2019). If needed, reinstall Office for Mac and activate by signing in with your Microsoft account.

Check activation limits (rare, but can look like a sign‑in loop). If you reached the install cap, de‑activate an older device at account.microsoft.com and retry in Word.

Tip: Keep all Office apps in /Applications. Moving them elsewhere can cause repeated keychain prompts and sign‑in failures.

If the error persists

Try step 3 (License Removal Tool) again, then sign in in Word first before opening other Office apps.

If you purchased via Apple but your Microsoft account isn’t recognizing it after restoring purchases, contact support (Microsoft or Apple) with purchase proof.

Hope this helps. Feel free to get back if you need further assistance.

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Hi Arun Gandhi

It has been a while and I am writing to see how things are going with this issue.

Have you had a chance to check the replies provided?

Any update would be appreciated.