The September 2026 security updates for Windows introduced instability in Remote Desktop Services, causing RDP connection and sign-in failures and unresponsive servers. Microsoft acknowledged these issues and released multiple out-of-band updates (KB5129194, KB5129195, KB5129236, KB5129235, KB5129237) on September 14, 2026, to address the RDS failures across Windows 10, Windows 11, and Windows Server 2022 and 2025. The updates also fix Hyper-V issues related to Host Compute Service-managed VMs and USB Audio Class 1.0 multichannel audio problems. Some USB audio issues remain and are being worked on by Microsoft. Prior to the fix, Microsoft provided Group Policy mitigations and noted that uninstalling the September updates restored RDS functionality but removed security fixes.

Affected systems experienced Remote Desktop Services failures, including RDP connection and sign-in failures, and in some cases, unresponsive servers. Related components such as Microsoft Management Console, RDS Licensing Diagnoser, File Explorer, and Windows Update page could become unresponsive. Hyper-V applications using Host Compute Service-managed VMs faced issues with shared folders in Linux guests. USB Audio Class 1.0 devices could fail to start or produce audio in multichannel modes, though stereo mode remained functional. These issues impacted system availability and usability but did not remove security protections if the updates were installed.

Microsoft has released official out-of-band updates to fix the RDS failures and related issues. Administrators should apply the relevant updates (KB5129194, KB5129195, KB5129236, KB5129235, KB5129237) available via Windows Update, WSUS, or Microsoft Update Catalog. Group Policy mitigations were previously provided but the permanent fix is now available. Uninstalling the September security updates restores RDS functionality but removes security protections and is not recommended. Some USB audio issues remain unresolved; Microsoft is working on further fixes.