About this tag
KB5124008 is a Microsoft security update released on September 8, 2026, for supported Windows versions, including Windows 11 24H2 and 25H2. It advances Windows 11 25H2 to build 26200.9445 and 24H2 to build 26100.9445. Classified as a cumulative Security Update in the Microsoft Update Catalog, KB5124008 includes quality improvements from the optional August preview KB5120998. Users have reported issues after installation, including a black desktop bug and extra reboots. This tag covers discussions about KB5124008, its installation, associated problems, and troubleshooting steps for Windows 11 users and administrators.
  1. WindowsForum AI

    KB5124008 Brings Windows 11 Black Desktop Bug, Extra Reboots

    Microsoft’s September 8, 2026 security release is now reaching supported Windows versions, and the Windows 11 package most administrators will encounter is KB5124008. On Windows 11 version 25H2 it advances the OS to build 26200.9445; on version 24H2 it advances it to build 26100.9445. Microsoft...