0x0 Error when trying to log on to Office 365 on MacOS 10.15.7

Hi Subir,

Currently, multiple users are experiencing the following error when attempting to activate Microsoft Office on Mac:

"Unknown Error: An unknown error has occurred. Error Code: 0x0".

This appears to be a more complex issue that may be originating from the service side. At this time, there are no known end-user workarounds that can reliably resolve this error.

Given the nature of the problem, I recommend reporting it to Microsoft Support so they can investigate further and determine whether it is related to a backend service issue. Doing so will also help ensure that Microsoft is aware of the impact and can provide updates or guidance as they become available.

If you're using a business account (@yourcompany.org, @onmicrosoft.com....), please ask your IT admin to raise a support ticket following this article: Get support - Microsoft 365 admin | Microsoft Learn

If you're using a personal account (outlook.com, Gmail, Hotmail....), please reach out to Microsoft Support team through Contact Us - Microsoft Support

I hope this issue get resolved as soon as possible. I'm glad to assist and truly hope the information provided has been useful. Please feel free to reach out anytime if you need further assistance.

Thank you for your kindness and contributions to the forum.

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Hi Subir,

Currently there has been an update and confirmation from Microsoft about this error. You can find the information about it here: Unknown Error 0x0 or License not found error in Microsoft 365 or Office running on macOS | Microsof…

The solution will depend on how your Microsoft Office apps are being updated and managed.

If you installed Microsoft 365 or Office from microsoft.com, follow these steps:

Ensure that you are running at least macOS version 12 or higher.

Close all Office applications.

Open the Microsoft AutoUpdate (MAU) from Finder > Applications > Microsoft AutoUpdate.

Note

If you don’t see MAU, check /Library/Application Support/Microsoft/MAU2.0/

If you want to learn about the details of each update before installing, select the arrow next to the Update button and review the apps, versions and installation date. Then select Update All or Update next to individual apps.

After the updates are complete, launch the Office application again to test.

If you installed individual Office apps from the App Store (less likely) follow these steps:

1. Ensure that you are running at least macOS version 12 or higher.
2. Close all Office applications.
3. Open the App Store.
4. Select Updates from the sidebar
5. Look for:
   • Microsoft Word
   • Microsoft Excel
   • Microsoft PowerPoint
   • Microsoft Outlook
   • Microsoft OneNote
6. Select Update next to each app or Update All.
7. After the updates are complete, launch the Office application again to test.

I hope this provides enough clarity and helps you stay inform with your current situation.

In the meantime, if you see my replies bring helpful information, please kindly accept it as an answer and vote it up by your original account, which raised this question. Once marked, it will automatically pin to top. As other users will also search information in this community, your valuable vote up will definitely also help other users who have similar queries easily to find the correct channel and useful information more quickly.   

Thank you for your patience and your understanding. If you have any questions or need further assistance, please feel free to share them in the comments on this post so I can continue to support you.