Microsoft says KB5120998 resets Windows desktop settings

Microsoft has confirmed that the optional KB5120998 preview update can cause desktop settings to fail to load or reset on some devices running Windows 11 24H2 and Windows 11 25H2.

The issue may affect wallpapers, desktop themes, slideshow settings, contrast themes, and other desktop settings. Microsoft said affected systems may display a solid black desktop background. Users also cannot manually restore their customized settings because the bug prevents Windows from loading the correct values.

KB5120998 was released on August 27 2026 with 35 changes and fixes, including improvements to the Start menu, taskbar, and Windows search. Microsoft acknowledged a related issue one day later in which the update changes or resets mouse settings and prevents affected users from restoring their previous settings.

Because KB5120998 is a non-security update, users normally need to select the Download and install link. However, it can install automatically when the Get the latest updates as soon as they're they're available option is enabled. Microsoft addressed a similar desktop wallpaper problem in February 2020 after the KB4539602 update affected Windows 7 wallpapers in Stretch mode.