365 STOPPED WORKING

On macOS, error 0x0 is a known Office/Microsoft 365 licensing issue. The supported fix is:

1. Verify the Mac is running macOS 12 or later.
2. Close all Office apps.
3. If Microsoft 365/Office was installed from microsoft.com, open Finder > Applications > Microsoft AutoUpdate and install all available updates.
   • If Microsoft AutoUpdate is not visible, check: /Library/Application Support/Microsoft/MAU2.0/
4. If the apps were installed from the App Store, open App Store > Updates and update the Microsoft apps there instead.
5. After updates finish, open Word or another Office app again and test activation.

Important:

• If the Mac is on macOS 11 or earlier, Office can enter reduced functionality mode and may no longer activate correctly. Updating the OS first is required.
• If Microsoft 365 has not connected to the internet for at least every 39 days, apps can show licensing problems or reduced functionality. Reconnect to the internet and sign in again.
• If a yellow Account Notice appears instead of only 0x0, check that the subscription is active and payment information is current.

If the Mac is already on macOS 12 or later and fully updated, the next step is to update Office through Microsoft AutoUpdate or the App Store, depending on how it was originally installed.

References:

• Unknown Error 0x0 or License not found error in Microsoft 365 or Office running on macOS | Microsoft Support
• Update Microsoft 365 or Office on your macOS or iOS device | Microsoft Support
• What's the difference between a paid Microsoft 365 subscription and the free web apps? | Microsoft Support
• A subscription notice appears when I open a Microsoft 365 application | Microsoft Support
• Office error "Account Notice: We've run into a problem with your Microsoft 365 subscription" | Microsoft Support