KB5066791 Rolls Out as Windows 10’s Final Update as Official Support Ends Today

Patch Tuesday is back, so does the last update for Windows 10. Microsoft has officially rolled out the final cumulative update KB5066791 for Windows 10, ending mainstream support for the decade-old OS.

The KB5066791 update, available now for versions 20H2, 21H2, and 22H2, brings the final round of bug fixes and security improvements. Once installed, your system builds will jump to 19044.6456 and 19045.6456.

What’s New in the Windows 10’s Final Patch Tuesday Update

The KB5066791 mostly focuses on reliability and security. Microsoft has fixed several long-standing issues with Input Method Editors (IMEs), ensuring that private Unicode characters now display correctly under the GB18030 standard.

Another fix addresses USER32 Edit controls, where certain character pairs appeared as empty boxes when text fields reached their length limit. Windows Remote Management also gets some attention, as a timeout bug affecting PowerShell Remoting and WinRM has been resolved.

A notable addition is a new Servicing Stack Update (SSU), which includes an improved certificate chain for Azure validation. Microsoft says this will ensure more consistent licensing verification across environments.

It’s worth noting that the ltmdm64.sys fax modem driver has been removed. Meaning, devices relying on this specific driver will no longer work after updating.

The end of an era

This marks the final “B release” for Windows 10. Microsoft confirmed that support officially ends today, with future updates only available to those enrolled in the Extended Security Updates (ESU) program.

Older LTSC editions, such as versions 1809, 1607, and 1507, also received their own cumulative updates today under KB5066586, KB5066836, and KB5066837, respectively.

Not fto forget, those enrolled in ESU will still be getting security updates until October 13, 2026. Speaking of feature updates, Microsoft is now fully focused on Windows 11 and the upcoming Windows 12.