Microsoft has confirmed that the KB5070311 preview update is triggering bright white flashes when launching the File Explorer in dark mode on Windows 11 systems.
“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,” Microsoft says in a Monday support document.
The bug is also triggered when navigating to or from Home or Gallery (including launching to Home), creating a new tab, toggling the Details pane on or off, and selecting ‘More details’ while copying files.
Microsoft is now working on a solution but hasn’t provided a timeline for the fix. Until a fix rolls out, affected users are advised to switch off dark mode to avoid getting flash-banged when launching File Explorer or creating new tabs.
The fact that Microsoft hasn’t caught and fixed this bug before releasing the KB5070311 optional update is quite surprising, given that it also rolls out with what the company describes as a “more consistent dark mode experience.”
According to Microsoft, the preview update has refreshed the copy, move, and delete dialogs in both default and expanded views. Progress bars and charts now match the dark theme for better readability, and confirmation and error dialogs have been updated for a consistent appearance.
As BleepingComputer reported earlier today, KB5070311 also addressed a bug causing the explorer.exe process and the taskbar to stop responding after certain notifications.
With this update, Microsoft also fixed a known issue behind File Explorer search failures on some SMB (Server Message Block) shares after installing recent Windows updates.
In November, Microsoft confirmed another critical bug that causes File Explorer, the Start Menu, and other key system components to crash when provisioning Windows 11 24H2 devices with cumulative updates released since July 2025.
Last month, it also announced that it had started testing a new optional feature that preloads the File Explorer in the background to improve performance and launch times on Windows 11 systems.
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