Microsoft has confirmed a significant bug within its recent KB5120998 August 2026 preview update. Following a surge of user complaints, the tech giant admitted that the update is causing desktop settings to be lost or reset on various Windows devices, leading to widespread frustration among users.

The most visible symptom of this glitch is the loss of personalized desktop wallpapers. Users have reported that immediately after the installation, their custom backgrounds are replaced by a solid black color. According to Microsoft's official release health update, this issue is not limited to wallpapers; it may also disrupt slideshow settings, contrast themes, and other desktop-related configurations.

Why This Matters

BozokMedia analysis shows that this bug creates a significant friction point for users attempting to maintain a personalized and functional workspace. The issue is particularly critical because it affects the latest builds of Windows 11 (24H2 and 25H2). Most importantly, the bug creates a loop where users attempt to fix the issue manually, but the system fails to load the customized values, defaulting back to a black screen regardless of user input.

Microsoft stated that the issue prevents the correct loading of settings, making it impossible for users to restore customized desktop environments on affected devices.

Beyond visual aesthetics, the KB5120998 update, which was released on August 27, 2026, was intended to bring improvements to the Start menu, taskbar, and Windows search. However, it has also been linked to unexpected changes in mouse settings that users are unable to revert.

Historical Background

This is not an isolated incident in Microsoft's history. A remarkably similar issue occurred in February 2020 with the KB4539602 update, which broke wallpaper functionality for Windows 7 users, causing 'Stretch' mode wallpapers to display as blank black screens.

How to Avoid the Issue

Since KB5120998 is an optional, non-security preview update, users can avoid the headache by not clicking 'Download and install' in the Windows Update settings. However, users who have enabled the 'Get the latest updates as soon as they're available' feature may find the update installing automatically.

Frequently Asked Questions

1. Can I fix my black wallpaper manually?
Currently, no. Microsoft has confirmed that manual attempts to restore settings fail because the bug prevents the settings from loading correctly.

2. Which Windows versions are affected?
The issue primarily impacts systems running Windows 11 versions 24H2 and 25H2.