Windows 11 Update Causes Black Screen After Sign-In

Microsoft has confirmed a new Windows 11 issue that can cause a black screen after users sign in, with affected systems sometimes failing to load the desktop automatically.

The problem has been linked to Windows 11 updates released from late August 2026 onwards and primarily affects Azure Virtual Desktop environments using Microsoft’s FSLogix profile technology.

Microsoft says the issue affects Windows 11 version 24H2, Windows 11 version 25H2 and Windows 11 version 26H1. It has been observed more frequently with some existing user profiles.

Affected users may see a black screen immediately after signing in because the desktop session does not start normally.

In some cases, users cannot access their Windows desktop until the session is started manually. Windows application event logs may also record crashes involving Windows Explorer.

Microsoft says the issue has mainly been reported on Azure Virtual Desktop hosts running FSLogix. FSLogix is commonly used in virtual desktop environments to manage and load user profiles.

For Windows 11 24H2 and 25H2, Microsoft traces the problem to the KB5120998 non-security preview update released on 27 August 2026.

Windows 11 26H1 is affected through KB5120996, Microsoft’s corresponding August preview update for that version of Windows. Microsoft’s Windows 11 release information lists KB5120996 as the August 2026 preview update for Windows 11 26H1 and KB5120998 for Windows 11 24H2 and 25H2.

The problem can also remain present after installing subsequent Windows updates because the underlying change introduced by the August preview updates is carried forward.

Microsoft has classified the issue as mitigated rather than fully resolved and says it is working on a permanent fix that will be included in a future Windows update.

Users who encounter the black screen can temporarily restore the Windows desktop by manually starting Windows Explorer.

To do this, users can press Ctrl+Shift+Esc to open Task Manager, select Run new task, type explorer.exe and select OK. Microsoft says this can temporarily mitigate the problem on affected systems.

Microsoft has also deployed a Known Issue Rollback, or KIR, to mitigate the faulty Windows change.

Known Issue Rollback allows Microsoft to disable specific non-security changes introduced through Windows Update without requiring the entire update to be removed.

For enterprise-managed computers, administrators need to install and configure a special Group Policy associated with the affected Windows version.

Windows 11 24H2 and 25H2 systems can use the KB5124010 Known Issue Rollback policy, while Windows 11 26H1 uses the KB5124006 KIR policy.

Microsoft says administrators must install and configure the appropriate Group Policy and restart affected devices for the mitigation to take effect. The policy disables the Windows change responsible for the problem until Microsoft releases a permanent resolution.

The issue should not be confused with another black-screen problem introduced by the KB5120998 update.

Microsoft previously confirmed that KB5120998 could cause customised Windows desktop backgrounds to disappear and be replaced by a solid black background. That problem affected Windows 11 24H2 and 25H2 and could also reset other desktop settings.

Microsoft fixed that separate issue with the September 2026 KB5124008 security update.

The newer problem is more disruptive because it affects the loading of the Windows desktop itself rather than simply changing the desktop wallpaper.

Microsoft’s documentation currently identifies Windows 11 24H2, 25H2 and 26H1 as the affected client platforms, with no Windows Server versions listed as affected.

For users running conventional Windows 11 PCs outside virtual desktop environments, Microsoft’s wording indicates that the problem has been primarily observed on Azure Virtual Desktop systems using FSLogix rather than broadly across all Windows 11 installations.

A permanent fix is expected through a future Windows update. Until then, affected organisations can use Microsoft’s Known Issue Rollback policy, while users who encounter the black screen can manually launch explorer.exe to regain access to the desktop.