Microsoft has fixed a Windows 11 bug that reset desktop settings and replaced users’ wallpapers with a solid black background.
The problem affected some devices running Windows 11 versions 24H2 and 25H2 after the installation of the optional KB5120998 preview update, released on 27 August 2026.
Microsoft said the fault prevented Windows from correctly loading customised desktop settings. As a result, users could lose their wallpaper, theme and other preferences, while attempts to restore them manually failed.
The update could also alter mouse settings and stop users from recovering their previous configurations after they had been reset.
Although KB5120998 required users to select “Download and install”, it could be installed automatically on devices where the option to receive the latest updates as soon as they become available was enabled.
Microsoft said the issue was resolved by the Windows updates released on 8 September, including cumulative update KB5124008, and urged users to install the latest security update.
“This issue was resolved by Windows updates released September 8, 2026 (KB5124008), and later,” the company said in a Windows release health update. It added that the update included “important improvements and issue resolutions, including this one”.
The company faced a similar desktop wallpaper problem in 2020, when a Windows 7 update caused wallpapers displayed in “Stretch” mode to appear as a blank black screen.
