Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
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Microsoft periodically updates the certificates used to sign Office applications and validate Microsoft 365 licensing. Here,
Office 2019 for Mac reached the end of support on October 10, 2023, and no longer receives updates. Because it cannot be upgraded to the latest version, this issue cannot be resolved by updating or reinstalling Office 2019.
Going forward, if your Mac is running macOS 12 (Monterey) or later, you will need to either upgrade to Office 2024 or purchase a Microsoft 365 subscription to continue using Office desktop apps on your Mac.
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