WSL fails to start - Catastrophic failure Error code: Wsl/Service/CreateInstance/E_UNEXPECTED

[notable-equivalent]

Windows Version

Microsoft Windows 11 Enterprise [Version 10.0.22631 Build 22631]

WSL Version

2.5.9.0

Are you using WSL 1 or WSL 2?

• WSL 2
• WSL 1

Kernel Version

6.6.87.2-1

Distro Version

Ubuntu 20.04

Other Software

No response

Repro Steps

Not sure of the root cause. On my machine typing wsl.exe -d Ubuntu gives the error.

Expected Behavior

WSL starts up the Ubuntu (20.04) distro.

Actual Behavior

WSL fails to start with an error:

Catastrophic failure
Error code: Wsl/Service/CreateInstance/E_UNEXPECTED

Other distributions work fine. This distribution was also working fine yesterday, and I can't think of anything I've done recently that would break it. Issue persists on restart.

Diagnostic Logs

WslLogs-2025-07-08_10-03-55.zip

[github-actions]

The logs shows that a disk mount error occurred. Try to follow these repair instructions and see if that solves the issue.

Diagnostic information

Detected appx version: 2.5.9.0
Detected user visible error: Wsl/Service/CreateInstance/E_UNEXPECTED
Found evidence of ext4 error: [ 1078.427994] EXT4-fs error (device sdd): ext4_validate_block_bitmap:421: comm LaunchDistro: bg 3629: bad block bitmap checksum

[notable-equivalent]

Issue was fixed by following those instructions. Needed to install a second distro to run e2fsck.

wsl.exe --install Ubuntu-24.04
wsl.exe --shutdown
wsl.exe -d Ubuntu-24.04 --mount "C:\Users\jsmith\AppData\Local\Packages\CanonicalGroupLimited.UbuntuonWindows_79rhkp1fndgsc\LocalState\ext4.vhdx" --vhd --bare
wsl.exe -d Ubuntu-24.04 lsblk
wsl.exe -d Ubuntu-24.04 sudo e2fsck -f /dev/sdd
wsl.exe -d Ubuntu-24.04 --unmount