Microsoft Rolls Out Fix for Windows 11 Update That Broke Claude Cowork

Microsoft released patch KB5129195 on Monday to fix problems caused by the September 8 Windows 11 update KB5124008, which broke USB audio, virtual machine shared folders, and Anthropic's Claude Cowork. The patch, delivered as OS Builds 26200.9457 or 26100.9457, fully resolves Remote Desktop Services and virtual machine issues but only fixes multichannel audio errors, leaving USB Audio 1.0 peripherals still unable to produce sound. Anthropic had warned that the update left Claude Cowork on Windows unable to run local commands because its workspace could no longer reach the computer's drive, though chat and file reading and editing still worked for most users.

Once again, Microsoft is fixing problems introduced in a Windows 11 update. This time, the company has rushed out a fix after the update triggered USB audio issues and broke functionality with the AI tool Claude Cowork and a way to run Linux within Windows. The problematic Windows 11 update, KB5124008 https://support.microsoft.com/help/5124008 , rolled out last Tuesday, but it wasn’t long before Microsoft began receiving reports about malfunctions. For consumers, the update has been flagged for causing older USB Audio 1.0 https://docs.nxp.com/bundle/AN14567/page/topics/usb audio class 10.html peripherals to fail to emit sound. They can also post an error message that says, “This device cannot start Code 10 ." The bigger problems involve enterprise customers and software developers. The update could also break a virtual machine https://www.pcmag.com/encyclopedia/term/virtual-machine functionality, which allows Windows to run another operating system, including Linux. Claude Cowork and the Windows Subsystem for Linux WSL https://au.pcmag.com/migrated-15175-windows-10/90072/windows-subsystem-for-linux-heads-to-the-microsoft-store were both affected. Claude developer Anthropic even posted a warning https://status.claude.com/incidents/r1pqn1kb4hvk : “A Windows update released September 8 has left Claude Cowork on Windows unable to run local commands, because its workspace can no longer reach your computer's drive. For most users, chat and file reading and editing still work.” Microsoft added that “affected virtual machines start normally, but folders shared from the Windows host using Plan9 a Linux process do not appear or cannot be accessed in the guest environment. Applications or sandbox environments that depend on these shared folders might display an error indicating that no Plan9 drive shares were mounted.” The final issue concerns Remote Desktop Services https://learn.microsoft.com/en-us/windows-server/remote/remote-desktop-services/overview RDS , which enterprises often use to remotely host and manage employee computers. Microsoft warned that “in some environments, RDS might become unstable, resulting in RDP connections failing after several minutes, sign-in issues, or servers hanging at 'Please wait for the Remote Desktop Configuration.'" On Monday, Redmond issued the patch KB5129195 https://support.microsoft.com/help/5129195 , which should download and install automatically on affected Windows 11 PCs as OS Builds 26200.9457 or 26100.9457. The fix is designed to fully resolve issues with Remote Desktop Services and virtual machines. However, it only fixes a few symptoms of the USB Audio problems, specifically an error that prevented the peripherals from using multichannel audio features, including 8-channel or 3D audio modes. The other issue of the peripherals failing to produce audio remains. “We are working to address the other symptoms and will update this documentation when more information is available,” the company says. Although Microsoft’s patch promises to resolve the bugs, it doesn’t address other problems that’ve been tied to the problematic Windows 11 update, including software driver issues with AMD Radeon GPUs, according https://www.windowslatest.com/2026/09/15/windows-11-kb5129195-emergency-update-is-out-after-microsoft-confirms-major-issues-with-the-september-2026-update-but-it-wont-fix-amd-gpu-error/ to Windows Latest. The incident also isn’t a great sign of the company’s commitment to improving https://au.pcmag.com/migrated-15175-windows-10/115673/we-need-to-improve-microsoft-admits-windows-11-has-too-many-annoying-bugs Windows 11, as some users have accused the OS of becoming saddled with bloat and AI features. However, Microsoft’s effort to clean up Windows has only reinforced concerns that the OS has a track record of releasing buggy updates. In a bit of irony, the earlier KB5120998 update was designed to fix an issue in an earlier update that could cause the desktop mouse cursor to randomly change https://au.pcmag.com/migrated-15175-windows-10/119598/latest-windows-11-update-can-cause-mouse-cursor-to-glitch in size. Plus, last week's KB5124008 https://support.microsoft.com/help/5124008 update was designed to fix nearly 1,000 software bugs and vulnerabilities