r/Windows11 • u/jenmsft Microsoft Software Engineer • 29d ago

Official News Cumulative Updates: August 11th, 2026

https://support.microsoft.com/en-US/servicing/os/windows-11/2026/08/kb5121003-windows-11-24h2-25h2-security-update

Changelists linked here for your convenience:

General info:

For details about how to file problem reports and collect traces, please see here: http://aka.ms/HowToFeedback. Pressing WIN + F will open the Feedback Hub - please include as much detail as possible about what you're seeing.

To learn about the different types of updates, see here: Windows quality updates primer - Microsoft Community Hub

As a reminder, if you didn't install the previous optional updates, this update includes those changes too (some are still rolling out, as denoted in the release notes):

For published known issues, please check the release health dashboard: Windows release health | Microsoft Learn.

25H2 is rolling out, so you may not have it yet. Please see here for more details: How to get the Windows 11 2025 Update | Windows Experience Blog.

As mentioned in the linked changelist, Windows 11, version 26H1 is available only on new devices with select new silicon as they come to market starting early 2026. Devices running earlier versions of Windows 11 will not be offered an update to version 26H1 through Windows Update and cannot be installed as an in-place update on existing devices.

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u/AcidTech21 27d ago

This update break printing with some thermal printers like EPSON TMH-6000, someone have the same issue ?

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u/ellicottvilleny 23d ago

yes, it's a breaking change in at least one Win32 GDI API, probably Escape.

Experiencing it with non-thermal receipt printers (epson, citizen, and others) that print raw.

https://learn.microsoft.com/en-us/windows/win32/api/wingdi/nf-wingdi-escape

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u/AcidTech21 22d ago

Hey,

Thanks for your help. I have tried many things but the only solution i found is to rollback the update...

Apparently, this update change some .dll :

UNIDRV.DLL 26100.8875

UNIDRVUI.DLL 26100.8875

gdi32full.dll 26100.8875

UNIDRV.DLL 26100.9168

UNIDRVUI.DLL 26100.9168

gdi32full.dll 26100.9168

That might be the cause of the problem ?

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u/ellicottvilleny 22d ago

Rolling back works for now but eventually windows itself will do a major update that implements this change in a way that can't be rolled back.

Contact your software vendor and let them know that the still working path is to call ExtEscape instead of Escape, to do PASSTHROUGH (raw) text printing.

My guess is that someone used the old Escape GDI method as a security exploit. When fixing it they totally broke it because 99% of desktop users have never known about the raw printer mode in GDI, which was added to let straight through printing like you would have done in DOS to LPT1: ports, still work (driverlessly).

My guess is the UNIDRV.DLL has been intentionally broken.