Windows 11 updates leave some Azure Virtual Desktop sessions on a black screen; Microsoft issues a rollback policy

Windows 11 updates leave some Azure Virtual Desktop sessions on a black screen; Microsoft issues a rollback policy

25 September 2026 — Microsoft has confirmed that some Windows 11 devices show a black screen after sign-in and never load the desktop, a fault it traces to the August 2026 non-security preview update (KB5120998) and every update since. The issue was opened on Microsoft's Windows release health dashboard on the evening of 24 September 2026, Pacific time, and reported by The Register on 25 September. Microsoft says it "has been primarily observed on Azure Virtual Desktop (AVD) hosts, using FSLogix" and appears more often with some existing user profiles.

Symptoms

• A black screen after sign-in, with the desktop session not starting on its own.
• Users cannot reach their desktop until it is started manually.
• The Application event log may show Windows Explorer crashes.

Affected versions are Windows 11 26H1, 25H2 and 24H2. Microsoft lists no affected Windows Server versions.

Microsoft's workarounds

• For a single user: open Task Manager (Ctrl+Shift+Esc), choose "Run new task", enter explorer.exe and select OK.
• For managed estates: deploy the Known Issue Rollback (KIR) Group Policy, which switches off the change behind the fault until a fix ships. Microsoft publishes "KB5124006 260924_20071 Known Issue Rollback" for Windows 11 26H1 and "KB5124010 260924_20021 Known Issue Rollback" for 25H2 and 24H2. The policy has to be installed, configured under Computer Configuration, Administrative Templates, and followed by a restart.

Microsoft says a resolution "will be released in a future Windows update" and has not explained the cause.

This is a separate problem from the Remote Desktop Services instability after the September security update (KB5124008), which Microsoft fixed with the out-of-band update KB5129195 on 14 September, and from the reset desktop backgrounds after the August preview, fixed in September.

Who is affected

Organisations running pooled or personal Windows 11 session hosts on Azure Virtual Desktop with FSLogix profile containers, the managed service providers that run those estates, and help desks fielding "black screen" calls after log-on.

What to do

• Check session hosts for Explorer crash events after sign-in and match them against the timing of the August preview or later updates.
• Deploy the KIR policy for your Windows 11 version to the affected host pools, and schedule the restart it needs.
• Give the help desk the Task Manager workaround as a script for affected users.
• Keep the KIR in place until Microsoft marks the issue resolved, then remove it after the fixing update is installed.
• If you are building new host images, test sign-in with existing FSLogix profiles before rolling them out.

Sources

• Microsoft Learn, Windows release health: Windows 11, version 25H2 known issues, "Devices might experience a black screen or desktop loading issues after sign-in" (opened 24 September, 18:47 PT) — 24 September 2026
• The Register: Windows update leaves some virtual desktops staring into the void — 25 September 2026