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Microsoft’s December 2025 Patch Tuesday update Windows 11 KB5072033 was supposed to deliver better security and stability. And for the most part, it did. But it also introduced a couple of frustrating bugs that quickly caught users’ attention.
The most common complaints?
White flashes in File Explorer while using Dark Mode
Networking failures in Windows Subsystem for Linux (WSL) when using third-party VPNs
While Microsoft addressed several long-standing issues, these two problems have become headline-worthy due to how disruptive they can be for everyday users and developers alike.
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Why It Matters
If you rely on File Explorer all day, sudden white flashes especially in low-light environments can be distracting and uncomfortable. For developers and power users, the WSL networking bug is even more serious, as it can break workflows entirely when VPNs are enabled.
These issues matter because:
They affect usability and productivity
Developers using WSL + VPNs may lose network access
Visual glitches can feel like system instability, even if your PC is technically secure
Knowing what’s happening (and how to fix it) can save you hours of frustration.
How to Do It
The good news? There are multiple ways to work around or completely fix these bugs. Whether you want a permanent solution or a temporary workaround, the steps below walk you through each option in a clear, practical way.
Let’s break down what’s actually going wrong and how you can deal with each issue step by step.
Understanding These Bugs
Before fixing anything, it helps to understand what triggered these problems in the first place.
File Explorer Flashes in Dark Mode
After installing the December 2025 updates, many users noticed a brief white flash when opening File Explorer or performing common actions such as:
Opening a new tab
Copying files
Switching between Home and Gallery
Toggling the Details pane
Why this happens:
A preview update expanded Windows’ Dark Mode behavior. During loading, File Explorer briefly displays a white background before the dark UI fully applies, making the flash especially noticeable in dark rooms.
WSL Networking and VPN Problems
Another major issue affects users running Windows Subsystem for Linux (WSL) alongside third-party VPNs.
When WSL is configured to use mirrored networking mode, some VPNs, such as OpenVPN or Cisco Secure Client, prevent traffic from reaching Linux processes. This results in errors like:
“No route to host”
This bug primarily impacts developers who depend on WSL for coding, containerization, or backend services.
How to Fix File Explorer Dark Mode Flashes
Install KB5072033
First, make sure you’re running the latest version of Windows 11.
Steps to install KB5072033:
Open Settings from the Start menu
Click Windows Update
Select Check for updates
Find KB5072033 and download it
Restart your PC
Apply the update
Once installed, most users report that the white flashes especially during basic File Explorer actions are significantly reduced or completely gone.
Switch to Temporary Light Mode
If the issue persists even after updating, switching to Light Mode can eliminate the flashing entirely.
How to switch modes:
Open Settings
Go to Personalization
Click Colors
Find Choose your mode
Select Light
It’s not ideal for dark mode fans, but it’s a reliable workaround until Microsoft releases a full fix.
Delay or Uninstall Problematic Updates
Some optional preview updates may worsen the flashing issue.
To uninstall a problematic update:
Open Settings
Go to Windows Update
Click Update history
Select Uninstall updates
Locate KB5070311 (or other preview updates)
Uninstall and restart your PC
This rolls your system back without affecting core security patches but be cautious not to remove critical fixes.
Pro Tip
Windows 11 December update introduced File Explorer dark mode flashes
WSL networking can break when third-party VPNs are enabled
Installing KB5072033 fixes most File Explorer issues
Switching to Light Mode is an effective temporary workaround
Uninstalling preview updates can restore stability
Wrapping up!
While Windows 11 KB5072033 delivers important security improvements, these bugs show that even well-tested updates can introduce unexpected issues. The File Explorer flashing problem is mostly cosmetic, but the WSL + VPN networking failure can seriously disrupt development workflows.
The key takeaway?
Stay updated but stay informed. Knowing which updates to install, delay, or uninstall gives you more control over your system’s stability.
Microsoft is likely to address these bugs in upcoming patches. Until then, the fixes above should help you keep things running smoothly.