Microsoft shares workaround for Windows domain login issues
Microsoft confirms September 2026 Windows updates trigger domain trust failures via Machine Identity Isolation and shares a workaround for Windows 11 enterprises.
Microsoft confirmed the September 2026 security updates (KB5124008 for Windows 11 24H2/25H2, KB5124012 for 26H1) cause Windows to honor Machine Identity Isolation enforcement settings, breaking domain trust on systems not connected to Windows Server 2025 domain controllers. Admins report valid credentials failing with domain trust and credential errors. The workaround requires disabling Machine Identity Isolation via the same management method that enabled it (Intune, group policy, or registry) and resetting the secure channel with Test-ComputerSecureChannel. Microsoft previously shipped out-of-band fixes for Remote Desktop, Hyper-V, and USB audio issues from the same updates.