Microsoft has released an out-of-band cumulative update KB5129242 for Windows 11, version 23H2, after Patch Tuesday. It fixes Remote Desktop Services failures, inaccessibility of shared folders in Hyper-V Linux systems, and multichannel audio failure on USB Audio Class 1.0 devices.
The out-of-band update KB5129242 (build 22631.7584) for Windows 11, version 23H2, addresses issues that appeared after the September release. The update is cumulative and includes all security fixes and improvements from the September 8, 2026 security update (KB5122880), as well as the following changes.
- Remote Desktop Services. Fixed an issue with Remote Desktop Services (RDS) that occurred after installing the September security update. In affected environments, the services were unstable: RDP connections and sign-ins failed, and related tools stopped responding.
- Hyper-V. Fixed an issue in applications using virtual machines managed by HCS: folders that the host computer shared with Linux systems via the Plan 9 protocol did not appear in the guest environment or were inaccessible.
- 8-channel and spatial audio. Fixed an issue where devices conforming to the USB Audio Class 1.0 standard, which worked properly in normal stereo mode, failed when using multichannel audio – 8-channel or spatial.
Some USB Audio Class 1.0 devices still do not start and do not play sound after the September update: Device Manager shows the error This device cannot start (Code 10), and volume adjustment does not work.
Servicing stack update. Along with the cumulative update, the servicing stack update KB5122879 (version 22621.7578) is installed, which improves the reliability of the Windows update installation process.
Installation via Windows Update. The out-of-band update KB5129242 is downloaded and installed automatically via Windows Update. To check, go to Settings > Windows Update and click Check for updates. The package is also available for manual download from the Microsoft Update Catalog.
| Feature / Change | Performance Increase/Decrease | Optimization | PC Speed | Gaming Optimization |
|---|---|---|---|---|
| Remote Desktop Services – fixed instability after September security update (RDP connections and sign-ins failed, related tools stopped responding) | 🟢 High increase (restores full RDS functionality; no more failed connections or hanging tools) | 🟢 High (service stability restored in affected environments) | 🟡 Medium (indirect – admin/remote workflows no longer blocked) | ⚪ Not applicable |
| Hyper-V – fixed Plan 9 shared folders not appearing/inaccessible in Linux guests managed by HCS | 🟢 Medium increase (host↔guest file sharing works again; removes I/O blockage) | 🟢 High (VM file-sharing path restored) | 🟡 Medium (affects VM environments only) | 🟡 Low–Medium (benefits dev/test and VM-based gaming setups) |
| 8-channel and spatial audio – fixed USB Audio Class 1.0 devices failing in multichannel/spatial mode (previously worked only in stereo) | 🟢 Medium increase (multichannel/spatial audio output restored on affected devices) | 🟢 Medium (audio pipeline compatibility improved) | ⚪ No impact | 🟢 High (spatial audio and 8-channel surround work again in games) |
| Known issue: some USB Audio Class 1.0 devices still do not start / no sound after September update (Device Manager error "This device cannot start (Code 10)", volume adjustment broken) | 🔴 High decrease (audio device completely non-functional) | 🔴 Regression (no workaround; device unusable) | ⚪ No impact | 🔴 High negative (no game audio on affected USB DACs/headsets) |
Find and Change Settings
| Setting | Where to find | How to change |
|---|---|---|
| Remote Desktop Services | Settings > System > Remote Desktop | To enable or disable Remote Desktop, open Settings > System > Remote Desktop and turn the toggle on or off. To manage RDS-related policies, open Group Policy Editor under Computer Configuration > Administrative Templates > Windows Components > Remote Desktop Services. |
| Hyper-V | Settings > System > Optional features | To install or remove Hyper-V, open Settings > System > Optional features, search for Hyper-V and select it to enable or disable the feature. Manage virtual machines through Hyper-V Manager. |
| 8-channel and spatial audio | Settings > System > Sound | To change audio channels or enable spatial sound, open Settings > System > Sound, select your output device, and choose Spatial sound or configure the audio format under Advanced settings. |
| USB Audio Class 1.0 devices | Settings > System > Sound | To troubleshoot a device that cannot start, open Settings > System > Sound and check the output device. Open Device Manager and update or reinstall the driver under Sound, video and game controllers. If the device shows Code 10, try uninstalling and reinstalling the driver. |
Official announcement on the Microsoft website.
The last 10 Windows updates:
| Update | Build | Version | Windows | Channel | Date |
|---|---|---|---|---|---|
| KB5124006 | 28000.3086 | 26H1 | Windows 11 | Preview | 2026-09-22 |
| KB5124010 | 26200.9550 | 26H2 | Windows 11 | Preview | 2026-09-22 |
| KB5124138 | 28120.3032 | 26H1 | Windows 11 | Experimental | 2026-09-18 |
| KB5124140 | 26220.9492 | 25H2 | Windows 11 | Beta | 2026-09-18 |
| KB5124137 | 26340.9502 | 26H2 | Windows 11 | Experimental | 2026-09-18 |
| KB5129242 | 22631.7584 | 23H2 | Windows 11 | Stable | 2026-09-14 |
| KB5129236 | 19045.7727 | 22H2 | Windows 10 | Stable | 2026-09-14 |
| KB5129195 | 26300.9457 | 26H2 | Windows 11 | Stable | 2026-09-14 |
| KB5129194 | 28000.2956 | 26H1 | Windows 11 | Stable | 2026-09-14 |
| KB5124115 | 26220.9472 | 25H2 | Windows 11 | Beta | 2026-09-11 |