WSL files removed after windows minor updates

[etshy]

I left work friday night and shutdown my pc with install update option.
It installed a few minor updates like Powershell 7.5.3, Defender updates etc.
And back today, there was missing files on my C:\Program Files\WSL folder and everything crashed because of that.

Missing files were:

• ./system.vhd
• ./tools/modules.vhd

I took these files from the latest .msi installer (inside cab2.cab and cab4.cab) and could replace them so it works now but it already happened to me after windows updates and it's kinda annoying to fix.

Is there any reason for these files to be removed over windows updates ?

[tigran-sargsyan-w]

Those files are part of WSL’s system distro (CBL-Mariner) and kernel payload. Some Windows/WSL updates can leave C:\Program Files\WSL\system.vhd and tools\modules.vhd missing or mismatched. The fix is to repair/update WSL so those images are re-provisioned.

---

What to do (safe order)

1. Update WSL from Microsoft’s web build, then restart the WSL VM:

wsl --update --web-download
wsl --shutdown

2. Repair WSL from Settings
   Settings → Apps → Installed apps → Windows Subsystem for Linux → Advanced options → Repair (try Reset only if Repair fails).

3. Reinstall/repair via MSI if needed
   Grab the latest wsl.msi from the official WSL releases and install over the top (this restores system.vhd and modules.vhd).

4. Confirm features are enabled, then reboot:

dism.exe /online /enable-feature /featurename:Microsoft-Windows-Subsystem-Linux /all /norestart
dism.exe /online /enable-feature /featurename:VirtualMachinePlatform /all /norestart

---

Why it happens

• Modern WSL uses a system distro (CBL-Mariner) that lives under C:\Program Files\WSL\ (system.vhd). If it’s missing, WSL can’t start and you’ll see errors like “Failed to attach disk … system.vhd”.
• tools\modules.vhd contains versioned kernel modules shipped with WSL. Mismatches or cleanup tools can remove them. Reinstall/repair restores the correct images.

---

After it’s fixed

• Check versions:

wsl --version
wsl --status

• If you use cleanup/AV tools, exclude C:\Program Files\WSL\.
• Keep WSL current with:

wsl --update

[etshy]

Hey thanks for all those explanations !
I tried to update with wsl --update but without the --web-download when I had the error but it didn't fix it. I guess the --web-download was necessary.

Last question does these methods to update wsl and restore missing files have a chance to corrupt/remove my Debian distro ?

Anyway good to know there is proper way to fix this. thanks again.

[tigran-sargsyan-w]

Glad it helped!

About --web-download
Yep — that flag pulls the latest WSL payload directly from Microsoft’s web release instead of relying on the Store-delivered bits. It’s useful when the local install is missing pieces (like system.vhd) or the Store version is lagging.

Will this corrupt/remove my Debian?
Short answer: No. The actions I suggested (wsl --update --web-download, MSI reinstall, and “Repair” in Settings) replace WSL’s program files and its system distro under C:\Program Files\WSL\. They don’t touch your user distros (like Debian), which live under your user profile or wherever you imported them.
The things that would remove a distro are Reset (in Settings for WSL) or wsl --unregister <DistroName> — neither of which we used.

If you want extra peace of mind, do a quick export before any repair:

wsl --export Debian debian_backup.tar

If you ever needed to restore it:

wsl --import Debian C:\WSL\Debian debian_backup.tar --version 2

After updating, you can verify everything with:

wsl --status
wsl -l -v

Then start Debian and you should be good to go.

If this helps, consider marking the answer as accepted so others can find it quickly.