Microsoft releases emergency Windows updates to fix RDS failures

Microsoft has released emergency out-of-band Windows updates to fix Remote Desktop Services failures caused by this month's security updates, along with Hyper-V and USB audio problems on some Windows versions.

The September 2026 security updates caused Remote Desktop Services (RDS) to become unstable on affected systems, leading to RDP connection and sign-in failures and, in some cases, unresponsive servers.

Microsoft previously acknowledged the issue after Windows administrators reported widespread RDS problems following the September updates.

Affected systems could also experience problems with related components and tools, including Microsoft Management Console (MMC), RDS Licensing Diagnoser, File Explorer, and the Windows Update page, which could stop responding.

Microsoft has now released multiple out-of-band updates on September 14 to fix the bug, including:

• Windows 11 26H1: KB5129194
• Windows 11 24H2 and 25H2: KB5129195
• Windows 10 21H2 and 22H2: KB5129236
• Windows Server 2025: KB5129235
• Windows Server 2022: KB5129237

The Windows Server updates address RDS failures introduced by September's KB5122871 update on Windows Server 2025 and KB5122882 on Windows Server 2022.

The company had previously provided Group Policy mitigations for affected Windows and Windows Server systems while it worked on a permanent fix.

Administrators also reported that uninstalling the September security updates restored Remote Desktop functionality, but it also removed the security fixes included with those updates.

The Windows 11 26H1 update, KB5129194, is available through Windows Update, Windows Update for Business, the Microsoft Update Catalog, and Windows Server Update Services (WSUS).

For Windows Server 2022 and Windows Server 2025, the out-of-band updates are available through the Microsoft Update Catalog.

Microsoft also released KB5129195 for Windows 11 24H2 and 25H2 and KB5129236 for Windows 10 21H2 and 22H2 to address the RDS failures affecting those systems.

Hyper-V and multichannel audio fixes

The out-of-band Windows 11 updates also resolve a Hyper-V issue affecting applications that use Host Compute Service (HCS)-managed virtual machines.

Microsoft says some applications experienced problems when sharing Windows host folders with Linux virtual machines using Plan9, causing shared folders to either not appear inside the guest environment or become inaccessible.

The updates also fix an audio issue affecting some USB Audio Class 1.0 devices when used with multichannel audio, including 8-channel and 3D audio modes.

Microsoft says affected devices continued to work as expected in standard stereo mode but could fail when switching to these multichannel configurations.

However, the emergency updates do not resolve all of the USB audio problems introduced by the September updates.

"After installing the September 8, 2026, Windows security update, some USB Audio Class 1.0 devices might fail to start or produce audio," Microsoft says in the release notes.

"Affected devices might experience one or more of the following symptoms: The device displays an error in Device Manager: "This device cannot start (Code 10)." No audio output. Volume controls are unresponsive or remain at zero. Sound settings are unresponsive or unavailable. This issue is limited to USB Audio Class 1.0 devices."

The company says it is working on a fix for the remaining audio problems.