Microsoft has acknowledged an issue affecting some Windows devices after the installation of the KB5120998 preview update released on August 27, 2026. This issue primarily impacts Windows 11 versions 24H2 and 25H2, causing desktop settings, including wallpaper and themes, to reset or be lost, often resulting in a solid black background. Users are unable to manually restore their customized settings due to the issue preventing the correct loading of settings. The KB5120998 update was intended to enhance the Start menu, taskbar, and Windows search but inadvertently introduced complications, including changes to mouse settings that cannot be restored. The update is optional but installs automatically for users with the "Get the latest updates as soon as they're available" feature enabled. A similar bug occurred in February 2020 with the KB4539602 update, which disrupted desktop wallpaper functionality.