To deal with the Remote Desktop Services (RDS) failures caused by the September 2026 security updates, as well as with Hyper-V and USB audio problems on certain versions of Windows, Microsoft has issued emergency out-of-band Windows updates.
The September 2026 security updates had caused RDS to become unstable on the affected systems, resulting in failures when attempting to connect via RDP and log in, and in some instances, the servers became unresponsive.
Microsoft published the solutions on September 14, following its earlier recognition of the problem and the prior provision of temporary Group Policy workarounds.
The RDS failures might also have an impact on other components such as the Microsoft Management Console, File Explorer, and the Windows Update page.
Windows RDS Failures and Emergency Updates
The September updates led to instability in RDS, causing failures when attempting to connect via RDP and problems with signing in, as well as making some servers unresponsive.
Affected systems might also encounter issues with other related components and tools, such as the Microsoft Management Console (MMC), the RDS Licensing Diagnoser, File Explorer, and the Windows Update page, which in some cases would stop responding.
Microsoft had earlier offered Group Policy workarounds as it developed a permanent solution, and administrators also noted that uninstalling the September security updates had restored Remote Desktop functionality, although this action had at the same time removed the security fixes that were part of those updates.
Microsoft released the following updates on September 14 to fix the bug:
- Windows 10 21H2 and 22H2: KB5129236
- Windows 11 24H2 and 25H2: KB5129195
- Windows 11 26H1: KB5129194
- Windows Server 2019: KB5129238
- Windows Server 2022: KB5129237
- Windows Server 2025: KB5129235
The updates to Windows Server remedy the RDS failures caused by the KB5122871 update for Windows Server 2025 and the KB5122882 update for Windows Server 2022.
How to Install the Updates and What Else They Fix
Availability varies by version:
- The update known as Windows 11 26H1, KB5129194, can be obtained via Windows Update, Windows Update for Business, the Microsoft Update Catalog, and Windows Server Update Services (WSUS).
- The out-of-band updates for Windows Server 2019, 2022, and 2025 can be obtained via the Microsoft Update Catalog.
- The updates KB5129195 for Windows 11 24H2 and 25H2 and KB5129236 for Windows 10 21H2 and 22H2 deal with the RDS failures on those systems.
The Windows 11 out-of-band updates also fix a Hyper-V problem that affected applications which used virtual machines managed by the Host Compute Service (HCS).
In some cases, applications had difficulties when sharing Windows host folders with Linux virtual machines via Plan9, the result being that the shared folders either did not show up in the guest environment or became inaccessible.
The same updates also correct an audio problem which affects certain USB Audio Class 1.0 devices when they are used with multichannel audio, such as in 8-channel and 3D audio modes. While the affected devices function normally in stereo mode, they may fail when switching to these multichannel settings.
Remaining USB Audio Issues and Fix Status
The emergency updates do not cure all of the USB audio problems caused by the September updates; according to the release notes, Microsoft states that “after the Windows security update of September 8, 2026, some USB Audio Class 1.0 devices may fail to start or may not produce audio”.
Devices that are affected could show an error in the Device Manager with the message “This device cannot start (Code 10)”, may fail to produce any audio output, have volume controls that do not respond, or have sound settings that are unresponsive.
The problem only affects USB Audio Class 1.0 devices, and Microsoft states that it is working on a fix for the remaining issues.
Out-of-band updates are now available via the channels specified for each version of Windows; these updates remedy the RDS failures, the Hyper-V shared folder issue, and part of the USB audio problem.
However, Microsoft has not set out a timetable for addressing the remaining failures of USB Audio Class 1.0 devices, stating that it is still working on this issue.
