![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(230.39999999999998, 11%, 32%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EAG%3C/text%3E%3C/svg%3E)
Microsoft 365 and Office | Install, redeem, activate | For home | MacOS
Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(128, 39%, 22%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EKH%3C/text%3E%3C/svg%3E)
Hi, Ashok Gupta
I understand you want to reinstall the Office copy you already paid for. However, there’s an important recent change to be aware of before downloading anything.
Starting July 13, 2026, a licensing-certificate issue can leave older Office apps on Mac unable to edit or save files. If this is why your Office 2019 became inactive, reinstalling it will not restore activation, because Office 2019 cannot receive the required update. Your documents are not lost because of this issue. See the current guidance.
The final Office 2019-compatible build was 16.78, but older advice recommending that installer as an activation fix no longer addresses this certificate problem.
For now, you can use Word, Excel, and PowerPoint for free in your browser. For desktop apps, the supported alternatives are Microsoft 365 or Office Home & Business 2024, which is a separate one-time purchase.
What exact activation message appears, and which macOS version are you using? That will help distinguish this issue from a different activation error.