Microsoft Confirms Preview Update Wipes Out Desktop Settings
Microsoft has acknowledged a bug in the KB5120998 preview update, released as part of its August 2026 optional patch rollout, that causes certain Windows devices to lose or revert desktop customizations after installation. Affected users report that settings like taskbar layout, wallpaper, and other personalization tweaks get reset without warning.
Because this is a preview (optional, non-security) update, it isn't pushed automatically to most machines, limiting the blast radius mostly to IT admins and enthusiasts who install these updates early to test upcoming changes before they become mandatory in the next Patch Tuesday release. Microsoft says it is investigating a fix but hasn't detailed a timeline or workaround yet.
This follows a pattern of recent Windows preview updates introducing unexpected side effects on personalization and UI settings.