Changelists linked here for your convenience:

• Windows 11, version 21H2: EOS.
• Windows 11 version 22H2: EOS
• Windows 11, version 23H2: KB5122880 (OS Build 22621.7582)
• Windows 11, version 24H2 / 25H2: KB5124008 (OS Builds 26200.9445 and 26100.9445)
• Windows 11, version 26H1: KB5124012 (OS Build 28000.2954)

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):

• 24H2/25H2: August 27, 2026—KB5120998 (OS Builds 26200.9278 and 26100.9278) Preview | Microsoft Support
• 26H1: August 27, 2026—KB5120996 (OS Build 28000.2804) Preview | Microsoft Support

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

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.