WSL Import Error after KB5065426 install

[phuffaker]

Windows Version

Microsoft Windows 10.0.26100.6584

WSL Version

2.6.1

Are you using WSL 1 or WSL 2?

• WSL 2
• WSL 1

Kernel Version

No response

Distro Version

Ubuntu 24.04

Other Software

No response

Repro Steps

Install WSL 2.6.1
Install KB5065426
run wsl --import test c:\wsl\ c:\wsl<wsl file name>

Expected Behavior

Import process should begin

Actual Behavior

Incorrect function
Error code: Wsl/Service/RegisterDistro/CreateVm/HCS/0x80070001

Diagnostic Logs

No response

[github-actions]

Logs are required for review from WSL team

If this a feature request, please reply with '/feature'. If this is a question, reply with '/question'.
Otherwise, please attach logs by following the instructions below, your issue will not be reviewed unless they are added. These logs will help us understand what is going on in your machine.

How to collect WSL logs

Download and execute collect-wsl-logs.ps1 in an administrative powershell prompt:

Invoke-WebRequest -UseBasicParsing "https://raw.githubusercontent.com/microsoft/WSL/master/diagnostics/collect-wsl-logs.ps1" -OutFile collect-wsl-logs.ps1
Set-ExecutionPolicy Bypass -Scope Process -Force
.\collect-wsl-logs.ps1

The script will output the path of the log file once done.

If this is a networking issue, please use collect-networking-logs.ps1, following the instructions in Collect WSL logs for networking issues

Once completed please upload the output files to this GitHub issue.

See Collect WSL logs (recommended method).

If you choose to email these logs instead of attaching them to the bug, please send them to wsl-gh-logs@microsoft.com with the GitHub issue number in the subject, and include a link to your GitHub issue comment in the message body, and reply with '/emailed-logs'.

[HQJaTu]

Install attempt:

wsl --install FedoraLinux-42
Downloading: Fedora Linux 42
Installing: Fedora Linux 42
Incorrect function.
Error code: Wsl/InstallDistro/Service/RegisterDistro/CreateVm/HCS/0x80070001

Versions:

wsl --version
WSL version: 2.6.1.0
Kernel version: 6.6.87.2-1
WSLg version: 1.0.66
MSRDC version: 1.2.6353
Direct3D version: 1.611.1-81528511
DXCore version: 10.0.26100.1-240331-1435.ge-release
Windows version: 10.0.26100.6584

Unfortunately, I cannot share diagnostic settings. This Azure VD is for work and I don't have permission to share any details of it.

[phuffaker]

WslLogs-2025-09-12_17-48-50.zip

Logs attached

[github-actions]

Diagnostic information

Detected appx version: 2.6.1.0
Detected user visible error: Wsl/Service/RegisterDistro/CreateVm/HCS/0x80070001

[wildlife-ai-adarsh]

Title:

WSL fails after KB5065426 (Windows 11 24H2 build 26100.6584) — system.vhd missing

---

Environment

• OS Version: 10.0.26100.6584 (Windows 11 24H2)

• Update: KB5065426 (installed 2025-09-10)

• WSL Package: MicrosoftCorporationII.WindowsSubsystemForLinux v2.6.1.0

• Features:

  • Microsoft-Windows-Subsystem-Linux → Enabled
  • VirtualMachinePlatform → Enabled

---

Steps to Reproduce

1. Install KB5065426 on Windows 11 24H2 build 26100.
2. Reboot.
3. Run any WSL command.

---

Expected

WSL runs normally, Ubuntu distro starts.

---

Actual

• wsl --version works and reports:

  WSL version: 2.6.1.0
  Kernel version: 6.6.87.2-1
  Windows version: 10.0.26100.6584
  

• wsl --list --verbose shows my Ubuntu distro (stopped, version 2).

• wsl.exe cannot launch Ubuntu because the kernel backing file is missing:

  dir "C:\Program Files\WSL\system.vhd"
  → File not found
  

• No Microsoft-Windows-Lxss/Operational event log is present.

---

Data Integrity

• My distro VHDX is intact:

  C:\Users\adars\AppData\Local\Packages\CanonicalGroupLimited.Ubuntu_79rhkp1fndgsc\LocalState\ext4.vhdx
  Size: ~60 GB
  

• So only the kernel provisioning / system.vhd is broken.

---

Impact

• WSL worked before KB5065426.
• Immediately after the update + reboot, WSL is unusable.
• This appears to be the same regression other users are reporting in build 26100.6584.

---

Request

Please confirm whether KB5065426 is known to break WSL and if a hotfix is in progress. Guidance on a safe workaround (other than uninstalling the cumulative update) would be appreciated.

---

[wildlife-ai-adarsh]

Found a fix from this thread using the right click > repair option on the msi. https://www.reddit.com/r/wsl2/comments/1lonesk/win_11_wsl2_looking_for_cprogram/

[HQJaTu]

I downloaded .msi for WSL 2.6.1, right-clicked Repair and no avail. This does not change anything. Installation of any OS fails either from downloaded file or directly from online.

[sptremblay]

I've the same issue with the system.vhd was missing after the upgrade.
I uninstalled WSL 2.6.1 and installed WSL 2.5.10, and it works... I don't know for how long. If I run wsl --update , the vhd file is deleted.

[phuffaker]

New Logs:

WslLogs-2025-09-17_16-05-42.zip

[github-actions]

Diagnostic information

Detected appx version: 2.6.1.0
Detected user visible error: Wsl/Service/RegisterDistro/CreateVm/HCS/0x80070001

[HQJaTu]

As I really need to get WSL2 working, attempting downgrade:

WSL version: 2.5.10.0
Kernel version: 6.6.87.2-1
WSLg version: 1.0.66
MSRDC version: 1.2.6074
Direct3D version: 1.611.1-81528511
DXCore version: 10.0.26100.1-240331-1435.ge-release
Windows version: 10.0.26100.6584

Running wsl --install FedoraLinux-42:

Downloading: Fedora Linux 42
Installing: Fedora Linux 42
Incorrect function.
Error code: Wsl/InstallDistro/Service/RegisterDistro/CreateVm/HCS/0x80070001

Nope. Nothing works.