Microsoft subsequently released an out-of-band update, KB5129195, for Windows 11 versions 24H2 and 25H2 to address some of these problems.
What Happened With the September 2026 Windows 11 Update?
The September 8, 2026 security update, KB5124008, caused several compatibility and functionality problems on some Windows 11 systems.
Microsoft confirmed issues involving:
- Remote Desktop Services
- USB Audio Class 1.0 devices
- Hyper-V Linux virtual machine host folder sharing
The exact symptoms depend on the hardware, Windows version and configuration of the affected computer.
1. Remote Desktop Is Not Working
One reported problem affected Remote Desktop Services (RDS). Some systems could experience instability or connection-related problems after installing the September update.
How to Fix Windows 11 Remote Desktop Problems
First, check whether the latest out-of-band update is installed.
- Open Settings.
- Go to Windows Update.
- Click Check for updates.
- Install KB5129195 when it is offered.
- Restart the computer.
Microsoft states that KB5129195 addresses the Remote Desktop Services issue introduced by the September security update.
2. USB Audio Is Not Working
Some USB Audio Class 1.0 devices can stop producing sound after the September 8 update.
Possible symptoms include:
- No sound from the USB device
- Device Manager showing Code 10
- Volume controls becoming unresponsive
- Windows Sound settings becoming unavailable
- Multichannel audio not working
Check Your USB Audio Device
- Press Windows + X.
- Select Device Manager.
- Expand Sound, video and game controllers.
- Find your USB audio device.
- Check whether Windows displays a warning icon.
Microsoft's September documentation says the out-of-band update partially resolves the USB Audio Class 1.0 problem, including symptoms involving 8-channel or 3D audio modes. Some other USB-audio symptoms may still require a later resolution.
Try Stereo Audio as a Temporary Workaround
If your USB audio device supports multiple audio channels, switching temporarily to a standard two-channel stereo configuration may restore audio on some affected systems.
Open your sound device settings and look for the available audio format or channel configuration. Choose a standard stereo option when available.
3. Hyper-V Linux Folder Sharing Is Not Working
Another known issue affects host folder sharing for Linux virtual machines running through Hyper-V.
If a shared Windows folder suddenly disappears inside a Linux virtual machine after the September update, the Windows update may be responsible.
What You Should Do
First install the latest available Windows update and restart the machine. Then test the shared folder again.
For business or development systems where the problem continues, check Microsoft's Windows release-health documentation for the latest mitigation and resolution status.
How to Check Your Windows 11 Version
You can quickly check your Windows version and build number.
- Press Windows + R.
- Type winver.
- Press Enter.
- Check your Windows version and OS build.
You can also go to Settings > System > About.
How to Check Whether KB5129195 Is Installed
- Open Settings.
- Go to Windows Update.
- Select Update history.
- Look under Quality Updates.
- Search for KB5129195.
Should You Uninstall the September Windows Update?
Uninstalling a security update should not be the first choice because Windows updates can contain important security protections.
Before removing an update, check whether Microsoft's out-of-band update or another official fix is available for your specific problem.
For business computers, test the update on an affected machine and follow your organization's normal update and recovery procedures.
Quick Windows 11 Troubleshooting Checklist
| Problem | What to Check |
|---|---|
| Remote Desktop not working | Install the latest Windows update and restart |
| USB headset or speaker has no sound | Check USB Audio device and install available fixes |
| Code 10 in Device Manager | Check USB Audio Class 1.0 device status |
| Hyper-V Linux shared folder missing | Install current updates and test the VM again |
| Windows version unknown | Run winver |
Frequently Asked Questions
What is KB5129195?
KB5129195 is an out-of-band cumulative update released for Windows 11 versions 24H2 and 25H2 to address several issues associated with the September 2026 update.
Why is my USB audio device not working after a Windows update?
Microsoft confirmed a problem affecting some USB Audio Class 1.0 devices after the September 2026 security update.
Why is Remote Desktop not connecting after the Windows 11 update?
The September 2026 update caused a known Remote Desktop Services issue on some systems. Microsoft's out-of-band update addresses that issue.
How do I check my Windows 11 build number?
Press Windows + R, type winver and press Enter.
Conclusion
Windows updates are important for security, but occasionally a new update can create compatibility problems. The September 2026 Windows 11 update is a good example.
If your Remote Desktop, USB audio or Hyper-V environment stopped working after the update, first check your Windows version and update history, then install the latest official Microsoft fixes available for your system.
Bookmark this page because Microsoft may update the known-issues documentation as additional fixes become available.
Disclaimer: This article is provided for general technical information. Update availability and symptoms can vary depending on Windows version, hardware and configuration.
Brand Disclaimer: Microsoft, Windows, and other brand names mentioned in this article are trademarks of their respective owners. This website is not affiliated with or endorsed by these companies. Windows 11 update problems, Windows 11 September 2026 update, KB5124008 problems, KB5129195, Windows 11 RDP not working, USB audio not working Windows 11, Hyper-V Linux folder sharing
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