Microsoft has confirmed that the last update shipped for Windows 10 version 1909 could break up Microsoft 365 apps on some devices.

Windows 10 version 1909 has reached the end of support, and the May 2021 Patch Tuesday was the final one for this particular operating system version.

The May 2021 cumulative update is KB5003169, also it obviously has a number of security improvements targeted at both the operating system and the pre-loaded components.

Microsoft has now confirmed that KB5003169 might cause problems with Microsoft 365 apps, explaining that an investigation has already been under way along with a full fix ought to be provided within an upcoming release.

"After installing this update and restarting your device, you may be not able to sign into some Microsoft 365 desktop client apps for example Microsoft Teams, OneDrive for Business and Microsoft Outlook. You might also receive an 80080300 error or "We ran into a problem. Reconnecting…" when attemping to authenticate or sign into Teams," Microsoft explains.

Full fix currently in the works

The company says that only Windows versions from the Microsoft 365 apps are influenced by the glitch, so if you run them on mobile, web, or any other non-Windows operating-system, things are said to be working properly.

Microsoft explains the workaround is as simple as it could be, because it only comes down to a method reboot to bring this normal again.

"To mitigate this issue on most devices, you can restart your device a second time. Most devices will sign into affected apps not surprisingly for all subsequent restarts following the first restart that completes installation of the update. If restarting does not mitigate the issue on your device, you can use the web versions from the apps," Microsoft says.

No ETA continues to be provided as to once the full fix could land for everybody.