Windows 11 preview update causes black screen after sign-in; Microsoft publishes workaround

Microsoft disclosed on September 24 (U.S. Pacific Daylight Time) that some devices applying the August 27 preview update for current versions of Windows 11 are experiencing a black screen after sign-in. The desktop fails to load properly, leaving users with only a black screen. The company has provided interim workarounds until a permanent fix arrives via a future Windows Update.

The trigger was the August 27 preview update. After applying it, Explorer.exe — the process responsible for the desktop — fails to launch upon sign-in, leaving users staring at a black screen. Microsoft's investigation indicates the issue occurs most frequently on Azure Virtual Desktop (AVD) hosts using FSLogix, with a tendency to reproduce more readily with existing user profiles.

Affected Scope and Causal Update

Microsoft's release health dashboard summarizes the affected scope and cause as follows:

Because Windows updates are cumulative, the problematic change has carried forward into the monthly security update (KB5124008) released September 8 and subsequent updates. Even environments that did not apply the preview update will receive the same change if they have applied monthly updates from September onward. Microsoft filed this known issue on September 24 U.S. Pacific time (September 25 Japan time), and also noted that explorer.exe crashes may be recorded in the application event log as a symptom.

Two Interim Workarounds

If this issue occurs, the first option is to manually launch the desktop. From the black screen, press Ctrl+Shift+Esc (or go through Ctrl+Alt+Delete) to open Task Manager, select "Run new task" from the File , type explorer.exe, and execute it to force the desktop to load.

The other workaround leverages a mechanism Microsoft has already begun applying called "Known Issue Rollback (KIR)." KIR rolls back only the specific change causing the problem. For internet-connected Windows 11 devices, a partial rollback is automatically delivered within up to 24 hours, temporarily resolving the issue.

However, KIR is only distributed automatically to non-enterprise devices that are not centrally managed by IT departments. It does not propagate automatically to enterprise-managed devices, so administrators must deploy the KIR policy definition (.msi) that Microsoft provides for each version, configure it as a Group Policy, and then restart the device.

For Windows 11 version 26H1: KB5124006 260924_20071 Known Issue Rollback

For Windows 11 versions 25H2 / 24H2: KB5124010 260924_20021 Known Issue Rollback

Policy propagation takes 90–120 minutes under the default Group Policy refresh interval. Running "gpupdate" on affected devices can expedite confirmation. Also note, somewhat confusingly, that setting the policy to "Disabled" is what enables the rollback. The causal change is only actually disabled after the policy is applied and the device is restarted.

A String of Windows 11 Update Problems

This black screen issue is the latest in a series of Windows 11 update-related problems that have persisted throughout 2026. According to market observers' compilations, the January update KB5074109 caused black screens, POP profile configuration errors in classic Outlook, AVD authentication failures, and an issue where File Explorer ignored desktop.ini custom settings; blue screens and boot failures were also confirmed on some PCs.

The March update KB5079473 broke Microsoft account sign-in, with ripple effects extending to Teams, OneDrive, Edge, and Office. It was fixed 11 days later by the out-of-band update KB5085516, but the optional preview KB5079391 released that same month was pulled due to an installation error loop. The April update KB5083769 triggered BitLocker recovery screens on some PCs, requiring multiple reboots.

Problems continued from May onward. KB5089549 failed to install on machines with less than 10 MB of free space on the EFI system partition, producing rollback error 0x800f0922. The June update KB5094126 caused boot failures and BitLocker recovery loops on HP business PCs, with over 150 reports within 48 hours, along with OneDrive sync failures and Recycle Bin issues affecting multiple Windows versions. The July update KB5101650 caused unexpected shutdowns, overheating, and battery drain on Dell business PCs due to conflicts with Intel drivers, prompting Microsoft to block the update on Dell devices.

Most recently in September, within days of KB5124008's release, issues were confirmed including Remote Desktop failures, USB audio anomalies, crashes in Linux and WSL applications, Active Directory domain problems, Excel copy function glitches, Explorer.exe crashes, and AMD GPU instability. An emergency update KB5129195 was released on September 14 but has not resolved all issues.

The timeline organized by update is as follows:

Stability Gap with Windows 10 Becomes Clear

Windows 10 was originally scheduled to reach end of support in October 2025, but Microsoft decided to extend support twice. The Extended Security Updates (ESU) program for consumers is offered free of charge, with security updates available until October 12, 2027. However, this extension applies only to consumer devices; the ESU program for business PCs is a separate paid offering, available on an annual basis for up to three years (through October 2028). Meanwhile, for gamers using NVIDIA graphics cards, the future of driver support for Windows 10 remains a point of concern.

For enterprise IT administrators, the first priority is to identify devices running the affected versions (26H1 / 25H2 / 24H2) and determine whether virtual desktop environments using AVD, FSLogix, or Citrix Profile Management are in use. Citrix has also addressed the same symptom in its own support documentation, noting that environments combining virtual desktop products with profile management solutions may continue to experience the symptom even after applying the September 14 out-of-band update. Thorough testing in a staging environment before applying updates, and maintaining awareness of KIR Group Policy configuration status, will help reduce response time when incidents occur.

KIR can only roll back non-security changes. Since this case meets that condition, administrators can stop the cause of the symptom without giving up September's security fixes. There is no need to uninstall the entire update. Microsoft has indicated that a permanent fix will be delivered in a future Windows Update, and affected environments should apply interim workarounds while monitoring for additional update information.

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