Windows 11 Optional Update KB5120998 Triggers Mouse Pointer and Wallpaper Issues
Microsoft's optional Windows 11 update KB5120998, released in August, has caused mouse pointer customization failures and desktop wallpaper resets for some users. The update, which introduces a movable taskbar and resizable Start menu, has led to reports of oversized white pointers and black wallpapers. Uninstalling the update resolves the issues, but Microsoft has not yet acknowledged them officially.
Microsoft's optional Windows 11 update KB5120998, released in August, introduces a movable taskbar, a resizable Start menu, and a more streamlined search box. After installing the update, some users have reported issues such as mouse pointer customization failures and abnormal desktop wallpaper settings. Based on user feedback, the problems appear to be widespread.
The most common complaint is that custom mouse pointers are reset to a large, white, Windows 98-style default pointer that cannot be restored. One user reported that after installing build 26200.9278 (KB5120998), high-DPI custom pointers disappeared and were replaced by a large white pointer; uninstalling the update resolved the issue. Other users reported similar phenomena, including an inability to change the pointer to anything other than the default style, a pointer that remained white and enlarged, accessibility options that had no effect, and a noticeably longer pointer tail.
Another major issue involves desktop wallpapers being cleared and replaced with a solid black background. Multiple users repeatedly mentioned this in Windows 11 discussion threads. One user said that both their desktop and laptop showed black wallpapers after installing the update, and they could only manually reset them; several others replied that they had encountered the same problem. Some users experienced both issues simultaneously, noting that the update changed the desktop background to black while slightly enlarging the standard mouse pointer. Another user said that even after manually restoring the wallpaper, the background reverted to black after logging off or restarting, and only uninstalling the update fully resolved it.
Not all devices are affected. Some commenters reported no issues on multiple devices. However, based on available feedback, the impact appears broader than typical minor update glitches.
A small number of users reported encountering DISM error 0x800f0915 when attempting to repair system images after installing the update. This error has appeared in previous Windows 11 versions for months and is usually caused by DISM being unable to access a valid repair source, rather than being a new issue introduced by KB5120998.
Microsoft software engineer Jen Gentleman responded in discussion threads that KB5120998 is an optional update; if users choose to skip it, the changes will still be delivered in the next mandatory update. Microsoft has not specifically mentioned the mouse pointer or wallpaper issues, nor listed them as known issues.
Currently, the only confirmed solution is to fully uninstall the update, which also means losing the new taskbar, Start menu, and search box improvements. Microsoft has not issued an official known-issues announcement or confirmed whether it will use the Known Issue Rollback mechanism to revert the problematic changes, and no clear timeline has been provided.