Excel for Mac cannot activate Microsoft 365 subscription (Unknown Error 0x0) while other Office apps work

Question

I'm using Microsoft 365 Personal on a Mac running macOS Monterey 12.0.1.

My Microsoft 365 subscription is active and has been working for years. Word, Outlook, and OneNote are all signed in with the same Microsoft account and continue to work normally.

Recently, only Excel stopped recognizing my subscription. When I open Excel, I receive a banner stating that a subscription is required to edit and save files.

I have tried the available activation options:

Sign in with the Microsoft account that owns my subscription. This results in:

"Unknown error"

  Error code: **0x0**
  
     "Unable to activate Microsoft 365."
     
     **Restore Previous Purchases.** This reports that the purchase was successful but cannot be associated with my Microsoft account, then loops back to Retry.
     

• Try Free for One Month. This appears to start a new Microsoft 365 subscription instead of recognizing my existing subscription, so I have not proceeded with that option (concerned about getting double charged).

At this point, Excel only allows me to view documents. I cannot edit or save any workbook.

Has anyone encountered this issue before? Is there a way to reset Excel's activation or licensing on macOS without affecting the other Microsoft 365 applications that are working correctly?

If additional information would help, I'm happy to provide it.

Answer 1

If your version of MacOS is Monterey, then the error you are seeing is caused by an update on the 13th of July, many people are seeing the exact same error (0x0) if you are unable to upgrade your MacOS to a newer compatible version, your Office apps will go into Read Only mode, on the link below the full details on that update are provided.

https://support.microsoft.com/office/update-microsoft-365-or-office-on-your-macos-or-ios-device-f418ae5d-bb5f-4078-b3d9-9340f5dd084e

The last version of Office that will work on MacOS Monterrey is 16.88, that is available on the long table on this link to all the downloadable versions from the Microsoft servers, you will need to uninstall the currently installed Office apps before installing that version of Office.

https://learn.microsoft.com/en-us/officeupdates/update-history-office-for-mac