If after a recent update your Microsoft Office on Mac no longer opens documents for editing and displays a cryptic "Unknown Error 0x0" or "License not found" — you are not alone. This is a well-known issue that has affected many users worldwide.
The most important thing to know: your license and
subscription are fine. This is not a problem with your account or your
computer, but a failure in Microsoft's licensing system.
Why did this happen?
The cause of the error lies in the change of the digital
certificate used to verify Office licenses on Mac. Microsoft updated its
licensing mechanism, and older versions of the apps simply stopped
"understanding" the new certificates. This issue affected Microsoft
365 users, as well as owners of one-time licenses for Office 2021 and 2024.
The glitch affected macOS users globally. The source of the
problem is on Microsoft's side, and the company has already released a fix in
the form of app updates.
How to fix Error 0x0
There are several ways to resolve the issue, from the
simplest to the more complex. Start with the first one and move down the list
if the previous method doesn't work.
Method 1: Update Office via Microsoft AutoUpdate
(fastest)
This is the primary and most effective method, which
resolves the problem in most cases.
- Close
all Office applications (Word, Excel, PowerPoint, etc.).
- Open
Microsoft AutoUpdate. You can find it in several ways:
- Via
Spotlight search (press Cmd + Space and type
"AutoUpdate").
- In
the Applications folder on your Mac.
- If
it's not there, check the folder: /Library/Application
Support/Microsoft/MAU2.0/.
- In
the window that opens, click the "Update All" button.
- Wait
for the download and installation of updates to complete.
- Restart
any Office application. The error should disappear.
Important: If you installed Office from the Mac
App Store, you need to update it through the App Store itself. Open the App
Store, go to the "Updates" tab, and update all Microsoft
applications.
Method 2: Complete Reinstallation of Office
If the update doesn't help or won't install for some reason,
the next step is a full removal and clean installation of Office.
Step 1: Fully remove Office
- Simply
moving the icons to the Trash often leaves behind "traces" that
can cause issues. It is recommended to follow Microsoft's official
instructions for a complete uninstall, which includes removing not only
the apps themselves but also library files.
- Simplified
approach: move all Office applications from
the Applications folder to the Trash and empty it.
Step 2: Reinstall Office from the correct source
This is critically important. The installation source must match where you
purchased the license.
- If
you have a Microsoft 365 subscription purchased directly from Microsoft:
- Go
to the portal at office.com.
- Sign
in with the same Microsoft account that holds the subscription.
- In
the upper right corner, click the "Install apps" icon and
select "Microsoft 365".
- If
you purchased or downloaded Office through the Mac App Store:
- Reinstallation
must only be done through the Mac App Store.
After reinstalling, open any application and sign in to your
Microsoft account.
Method 3: Reset the license using Microsoft's official
tool
Microsoft offers a special tool to remove license files.
This can help without resorting to a full reinstall.
- Download
and run the Microsoft License Removal Tool from the
official Microsoft support website.
- The
tool will automatically find and remove all Office license files on your
Mac.
- Open
any Office application (e.g., Word) and sign in to your account again to
activate it.
Important nuances and compatibility check
Before taking any action, make sure your Mac meets the
minimum system requirements.
- macOS
version: For Office to work correctly and receive updates, you
need macOS 12 (Monterey) or newer. If you have an older
version, you won't be able to update Office. The only solution may be to
use the free web version of Office at microsoft365.com.
- Office
version: After the update, the installed version should be 16.83
or higher.
Error 0x0 is an unpleasant but solvable glitch. In most cases, the issue is fixed by a simple update through Microsoft AutoUpdate. If that method doesn't work, follow the step-by-step reinstallation guide, strictly adhering to the correct download source.
