how to fix this issue in mac?

Update Outlook using the updater associated with its installation source; if the warning remains and Outlook came from the Mac App Store, replace it with Microsoft’s direct-download Office 2021 build.

1. Update macOS and Office first

A July 2026 issue can place Office 2021 and other Office releases into reduced-functionality mode, so complete this check before reinstalling. macOS 12 or later is required for the documented update resolution.^1^

1. Select Apple menu → About This Mac and verify that macOS is version 12 or later. If it is older, update macOS where the Mac supports it.
2. Quit Outlook and every other Office application.
3. Update according to where Outlook was installed:
   • Installed directly from Microsoft: Open Finder → Applications → Microsoft AutoUpdate, then select Update All. If it is absent there, check /Library/Application Support/Microsoft/MAU2.0/.
   • Installed from the Mac App Store: Open App Store → Updates, then update Outlook and the other Office applications.
4. Reopen Outlook and check whether the activation banner is gone.

Microsoft lists current Outlook for Mac issues and fixes on its known-issues page.^2^

2. If Outlook is the Mac App Store version

The banner specifically says that the Office 2021 license is unsupported by this application version. A perpetual Office 2021 license cannot activate Office applications downloaded from the Mac App Store; those builds require a Microsoft 365 subscription. Install the direct-from-Microsoft Office 2021 build instead.^3^

1. Quit Outlook, Word, Excel, and PowerPoint.
2. Open Finder → Applications.
3. Control-click each installed Office application and select Move to Trash.
4. Download the Office 2021 for Mac Installer.
5. Open the downloaded package from Finder → Downloads.
6. Select Continue, accept the license agreement, and select Install. Enter the Mac administrator password if prompted.
7. Open an Office application and sign in with the Microsoft account associated with the Office 2021 purchase to activate it. The standard installation and activation sequence is documented here.^4^

Do not reinstall the Office applications from the Mac App Store unless switching to a Microsoft 365 subscription.

3. If activation still selects the wrong license

Use this only if the direct-from-Microsoft Office 2021 build is installed but Outlook still shows the wrong license.

Caution: The License Removal Tool removes all Office licenses from this Mac. Have the Microsoft account and password associated with the Office 2021 purchase available first.

1. Quit all Office applications.
2. Download Microsoft’s License Removal Tool.
3. Open the .pkg file from Finder → Downloads.
4. Select Continue, follow the prompts, and enter the Mac administrator password when requested.
5. After removal completes, open Outlook and sign in with the account that owns Office 2021.
6. If prompted to choose between Microsoft 365 and a one-time purchase, select the license actually owned.
7. Restart the Mac after activation.^5^

References

1. Unknown Error 0x0 or License not found error in Microsoft 365 or Office running on macOS | Microsoft Support
2. Fixes or workarounds for recent issues in Outlook for Mac | Microsoft Support
3. Microsoft Office activation and the Mac App Store | Microsoft Support
4. [Office for Mac 2021](https://support.microsoft.com/office/lifecycle/officeinstall/download-and-install-or-reinstall-office-2021-office-2019-or-office-2016)
5. How to remove Office license files on a Mac | Microsoft Support