Microsoft’s Patch Tuesday Broke Windows. Here’s the Emergency Fix.
Microsoft’s September 8 Patch Tuesday, described as one of the largest security updates in Windows history, patching nearly 1,000 flaws — immediately began breaking things. Within hours of deployment, IT administrators across the world reported that Remote Desktop Services had stopped working, shared folders between Hyper-V hosts and Linux virtual machines had disappeared, and USB audio devices had gone silent.
On September 14, Microsoft released an emergency out-of-band update to fix the damage. If your Windows machine applied the September 8 update and you haven’t installed the emergency fix yet, you need to do it now.
What the September 8 Update Broke
Three distinct problems emerged immediately after the Patch Tuesday rollout.
Remote Desktop Services (RDS). This was the most disruptive failure. RDS — the technology that lets users access a Windows machine remotely — became unstable across Windows Server 2019, 2022, and 2025. Connections started failing intermittently, servers got stuck in the “Please wait for the Remote Desktop Configuration” phase, and existing sessions couldn’t disconnect properly. For businesses running remote workforces or using terminal servers, this effectively shut down operations. The only workaround before the emergency fix was to uninstall the September update entirely — which meant leaving systems unpatched against the security vulnerabilities the update was supposed to close. Associated tools including Microsoft Management Console, RDS Licensing Diagnoser, File Explorer, and the Windows Update page also stopped responding on affected systems.
Hyper-V and Linux VM folder sharing. Windows 11 users running Linux virtual machines through Hyper-V found that folders shared from the Windows host using the Plan9 protocol stopped appearing inside the Linux environment. For developers using Windows as a host and Linux as a development environment, this broke established workflows immediately.
USB Audio Class 1.0 devices. Certain USB audio devices stopped working after the September 8 update — specifically devices using the USB Audio Class 1.0 standard in 8-channel or 3D audio modes. Standard stereo continued working, but multichannel audio configurations failed. For gaming setups, home studios, and professional audio environments, this was an unwelcome surprise from a routine security patch.
This is the fifth time in 2026 that Microsoft has had to release an out-of-band emergency update to fix damage caused by its own Patch Tuesday. January required four separate interventions. March brought two. July added another. September makes five incidents across nine months.
What the Emergency Fix Actually Covers
Microsoft released out-of-band cumulative updates on September 14 covering Windows 10, Windows 11, and Windows Server. The updates fix the RDS instability and the Hyper-V Plan9 folder-sharing failure completely. The USB audio situation is only partially resolved — 8-channel and 3D audio modes are working again, but some USB Audio Class 1.0 devices still fail to start. Microsoft acknowledged the remaining audio problems and said a complete fix is still coming.
The emergency update also closes two additional security vulnerabilities: CVE-2026-62721, a Windows User-Mode Power Service elevation of privilege vulnerability, and CVE-2026-85921, patched in the Windows 11 26H1 update.
The specific update numbers are: KB5129195 for Windows 11 24H2 and 25H2, KB5129194 for Windows 11 26H1, KB5129242 for Windows 11 23H2, KB5129236 for Windows 10 21H2 and 22H2, KB5129235 for Windows Server 2025, KB5129237 for Windows Server 2022, and KB5129238 for Windows Server 2019.
How to Install the Fix Right Now
The emergency update should be available through Windows Update. Open Settings, go to Windows Update, and check for updates. The fix is a cumulative update, meaning you can install it directly even if you haven’t yet installed the September 8 Patch Tuesday update — you’ll get the security fixes from both in one install.
For Windows Server environments, administrators can deploy the update through Windows Server Update Services or Microsoft Endpoint Configuration Manager using the standard process for out-of-band updates. For systems where automatic updates are enabled, the update may already be present on the machine, check the update history to confirm it has been installed, not just downloaded.
If your system was rolled back to remove the September 8 update as a workaround for RDS failures, apply the emergency update now to restore both RDS functionality and the security protections that were temporarily removed. For more on keeping your systems protected, see our guide on protecting yourself from AI-powered cyber threats and our coverage of Microsoft’s record June Patch Tuesday.
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