Recently, Microsoft released the preview update KB5070311 for Windows 11 version 24H2/252 — only for users who manually check for updates. Almost immediately, the update was found to introduce a flaw that severely disrupts the user experience: when the system is set to dark mode, launching File Explorer triggers a sudden flash of bright white.
Because KB5070311 is a preview update, it installs only when a user explicitly clicks “Check for updates.” Those who avoid doing so will not receive it — a reminder that one should resist casually pressing that button without reason.
In its support documentation, Microsoft states: “After installing KB5070311, you might experience issues when opening File Explorer in dark mode. The window might briefly display a blank white screen before loading files and folders.”
The same issue may occur when navigating to Home or Gallery (including launches that open directly to Home), creating a new tab, opening or closing the Details pane, or selecting “More details” while copying files.
Notably, the release notes for this preview update claimed to deliver a more consistent dark mode experience. Yet this glaring flaw suggests that the feature received insufficient testing before release — otherwise such an obvious issue would not have slipped through.
Microsoft has begun working on a fix, but has not provided a timeline. Fortunately, the problem was caught early; with any luck, it will not make its way into the December stable update, sparing the broader user base from encountering this disruptive bug.