Overview
- The September 8, 2026 security update KB5124008 caused multiple regressions that left some USB Audio Class 1.0 devices unable to start or produce sound and produced problems in Remote Desktop, WSL/Hyper‑V, Explorer and File History.
- Microsoft released out‑of‑band updates (KB5129194, KB5129195 and related KBs) on September 15 to fix many reported faults and to add security patches that were omitted from the original roll‑out.
- Despite the emergency patches, some USB Audio Class 1.0 devices still fail with “This device cannot start (Code 10)” or remain silent and Microsoft continues active remediation for those cases.
- Microsoft recommends administrators install the out‑of‑band updates quickly and offers temporary workarounds such as switching affected devices to 2‑channel stereo instead of uninstalling the September update.
- The problems grew out of an unusually large September Patch Day that fixed nearly 1,000 vulnerabilities and increased complexity for testing, forcing IT teams to weigh immediate stability against leaving critical security holes unpatched.