Microsoft has confirmed that desktop settings are lost or reset on some Windows devices after installing the KB5120998 August 2026 preview update.
Microsoft's confirmation follows a wave of user reports saying their wallpaper switched to a black background automatically after installing this Windows update.
The known issue impacts systems running Windows 11 24H2 and Windows 11 25H2, and it may affect the wallpaper, the desktop theme, and various other settings.
"Following installation of Windows updates released August 27 2026 (KB5120998) and later, some Windows Desktop settings fail to load, resulting in desktop backgrounds displaying as a solid black color," Microsoft said in a Windows release health update on Wednesday. "It is possible other desktop settings may be affected, such as slideshow settings or contrast themes."
According to Microsoft, because of this bug, users will also be unable to restore their custom settings on affected devices.
"On affected devices, attempting to manually restore customized settings does not work. This is because the issue prevents the correct loading of settings, regardless of their value. In this case, a default black background is used instead," the company added.