Microsoft confirms a bug in the KB5070311 preview update that results in a bright white flash when File Explorer is launched in dark mode on Windows 11. This happens when you run an app, open a new tab, or interact with a dialogue box.
This was after installing KB5070311, as Microsoft has stated in a Monday support page where users may encounter problems when opening File Explorer in dark mode. “The window may briefly display a blank white screen before loading files and folders.”
The error is also triggered when you navigate to or from Home or Gallery (including launching to Home), open a new tab, turn on or off the Details pane, or click ‘More details’ while transferring files.
Microsoft is currently working on a remedy, but no date has been offered. Affected users should disable dark mode until a fix is available to avoid being flash-banged while starting File Explorer or creating new tabs.
It’s strange that Microsoft didn’t catch and address this flaw before publishing the KB5070311 optional update, especially because it also includes what the company touts as a “more consistent dark mode experience.”
Microsoft reports that the preview version has refreshed the copy, move, and delete dialogues in both normal and enlarged views. To improve readability, progress bars and charts now match the dark theme, and confirmation and error dialogues have been modified to have a uniform appearance.
Earlier today, BleepingComputer reported that KB5070311 addresses a flaw that made the taskbar and explorer.exe stop responding after some notifications.
Microsoft also addressed a known issue that caused File Explorer search failures on select SMB (Server Message Block) shares after installing recent Windows updates.
Microsoft identified another serious flaw in November, causing File Explorer, the Start Menu, and other important system components to break when provisioning Windows 11 24H2 devices with cumulative upgrades delivered since July 2025.
Last month, it also stated that it has begun testing a new optional feature that preloads the File Explorer in the background to boost performance and launch times on Windows 11 machines.
It is recommended that since KB5070311 is an optional preview update, users who rely heavily on dark mode, due to one reason or the other, and wish to avoid this inconvenience can simply skip installing the update for now as the next mandatory Patch Tuesday security update is scheduled for December 9, which is just some days to come, and the fix might be included then, or in January 2026.