Microsoft has identified a bug in recent Windows 11 updates that leaves users facing a black screen after login because the desktop interface fails to load. The issue primarily affects Windows 11 versions 24H2, 25H2, and 26H1, appearing after the installation of optional update KB5120998 or subsequent cumulative updates. Affected users can currently recover access by manually launching explorer.exe via the Task Manager.
This isn’t a total system crash. It’s a shell failure. When you log in, the kernel is running and your session is active, but the graphical user interface—the part you actually see and touch—refuses to initialize. For most, this manifests as a void with a blinking cursor. It’s a frustrating gap between a successful boot and a usable desktop.
KB5120998 and the Azure Virtual Desktop Conflict
The glitch first surfaced with the optional update KB5120998, which rolled out on Aug. 27, 2026. While it can hit various setups, Microsoft reported the problem is most prevalent on Azure Virtual Desktop hosts using FSLogix. The company noted that existing user profiles seem to trigger the failure more frequently.
The symptoms are consistent across the affected builds. Users report that the desktop doesn’t launch automatically after connection, leaving them stuck. Event logs typically show Explorer crashes, confirming that the process responsible for the taskbar, Start menu, and desktop icons is simply dying on arrival.
Manual Recovery via Explorer.exe
Because the core OS is still functioning, users can bypass the black screen using a specific keyboard sequence. Laptopspirit.fr notes that seeing a moving mouse cursor is a key diagnostic sign; it proves the session is active and only the shell is broken. To fix this manually, press Ctrl + Shift + Esc to open the Task Manager.
Once the Task Manager is open, users should select “Run new task” and type explorer.exe. Clicking OK forces the Windows Explorer process to start, which typically brings the desktop back into view immediately. Laptopspirit.fr explains that this works because the Ctrl + Alt + Delete or Ctrl + Shift + Esc menus are handled by the Windows kernel, making them independent of the crashed graphical interface.
Enterprise Mitigations and Known Issue Rollbacks
Microsoft has deployed a Known Issue Rollback (KIR) to address this. This mechanism allows admins to revert the specific problematic change via Group Policy without uninstalling the entire update.
- Windows 11 26H1: A specific KIR policy is available for this version.
- Windows 11 24H2 and 25H2: A separate policy covers these two builds.
Deploying these policies requires a system restart to take effect.
The Root Cause of Shell Failures
The failure of explorer.exe usually stems from conflicts between new system updates and existing graphics drivers or registry entries. When a cumulative update modifies a system service, it can create a mismatch that prevents the shell from hooking into the display driver.
Microsoft is currently developing a permanent fix. However, the company has not provided a specific release date for the patch. Until then, users on the 24H2, 25H2, and 26H1 branches should be cautious with optional updates if they rely on virtualized desktop infrastructure.
