[DOCS] Missing troubleshooting guide for Cowork "VM service not running" + EXDEV errors on Windows

Documentation Type

Missing documentation (feature not documented)

Documentation Location

https://docs.anthropic.com/en/docs/claude-code/troubleshooting

Section/Topic

Cowork Windows troubleshooting — VM service and EXDEV errors

Current Documentation

The troubleshooting page at docs.anthropic.com does not mention any Cowork workspace errors on Windows. There are 30+ open issues on GitHub about "VM service not running", "signature verification failed", and "EXDEV: cross-device link not permitted" with no official documentation on how to fix them.

What's Wrong or Missing?

There is no troubleshooting documentation for Cowork workspace errors on Windows. After fixing these issues myself and helping others in multiple GitHub issues, here is a complete guide that should be added to the docs:

Who is this for?

If you're getting any of these errors:

• "VM service not running. The service failed to start"
• "signature verification initialization failed: failed to get service executable path"
• "EXDEV: cross-device link not permitted"
• "Incorrect function" (ExitCode 1066)
• Cowork stuck at ~80% on "Setting up Claude's workspace"

Step 1: Update Windows

Open PowerShell and run winver to check your build. Make sure you have the latest cumulative update installed. In my case, installing KB5086672 (build 26200.8117) was key.

Go to Settings > Windows Update and install everything available.

Step 2: Activate Windows

If your Windows is not activated, activate it. This can affect MSIX package permissions.

Step 3: Check your app storage location

This is the one nobody talks about. Go to:

Settings > System > Storage > Advanced storage settings > Where new content is saved

If "New apps will save to" is set to any drive other than C:\, that's your problem. Change it to C:\.

Why? When apps are set to save on D:\, Windows creates symlinks inside the MSIX package folder pointing to D:\. When Claude tries to move downloaded files with rename(), it fails because you can't rename across drives.

How to verify:

Get-ChildItem "$env:LOCALAPPDATA\Packages\Claude_pzs8sxrjxfjjc" | Format-Table Name, Attributes, Target

If you see symlinks pointing to D:\WpSystem\... → that's the cause of EXDEV.

Step 4: Enable required features

Run in PowerShell as Admin:

wsl --install
Enable-WindowsOptionalFeature -Online -FeatureName HypervisorPlatform -All
Enable-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V -All

After installing WSL, set Ubuntu as default:

wsl --set-default Ubuntu

Step 5: Clean uninstall

Get-AppxPackage -Name "Claude" | Remove-AppxPackage
Remove-Item "$env:APPDATA\Claude" -Recurse -Force -ErrorAction SilentlyContinue
Remove-Item "$env:LOCALAPPDATA\Claude" -Recurse -Force -ErrorAction SilentlyContinue
Remove-Item "C:\ProgramData\Claude" -Recurse -Force -ErrorAction SilentlyContinue
Remove-Item "$env:LOCALAPPDATA\Packages\Claude_pzs8sxrjxfjjc" -Recurse -Force -ErrorAction SilentlyContinue
Remove-Item "D:\WpSystem\*\AppData\Local\Packages\Claude_pzs8sxrjxfjjc" -Recurse -Force -ErrorAction SilentlyContinue

Step 6: Reboot and reinstall

1. Restart your PC
2. Download Claude Desktop from claude.ai/downloads
3. Right click > Run as Administrator
4. Let it finish completely
5. Open Cowork

How to verify it's working

Check the service log:

Get-Content "C:\ProgramData\Claude\Logs\cowork-service.log" -Tail 20

You should see:

[Server] Signature verification initialized [Server] Client signature verified Service ready. Listening on \\.\pipe\cowork-vm-service [VM] VM started successfully

Quick reference

| Error | Cause | Fix |
|-------|-------|-----|
| signature verification failed | Windows not updated or not activated | Update Windows + Activate |
| EXDEV: cross-device link | App storage on different drive | Change to C:\ in storage settings |
| VM service not running | Combination of above | Follow all steps |
| Incorrect function (1066) | Same as signature verification | Update Windows + Activate |

Related issues this fixes

#37312 #29941 #32481 #27897 #38396 #32186 #30584 #36642 #25476 #36522 #40254 #38241

Confirmed working by: @AmerSarhan (issue #32481, closed as resolved)

Tip: If you have Claude Code in VS Code or terminal, you can ask it to help diagnose your system. That's how I found the symlinks to D:\ — it can run PowerShell commands and check for residual files across drives.

Suggested Improvement

The troubleshooting documentation should include a section for Cowork workspace errors on Windows, covering:

1. How to diagnose "VM service not running" and "signature verification failed" errors
2. How to fix EXDEV cross-device link errors during workspace setup
3. How to verify app storage location and MSIX package symlinks
4. Complete clean uninstall and reinstall steps

The full step-by-step guide is provided in the "What's Wrong or Missing" section above.

Impact

High - Prevents users from using a feature

Additional Context

Related GitHub issues with users affected by this (30+ reports):

• #37312 #29941 #32481 #27897 #38396 #32186 #30584 #36642 #25476 #36522 #40254 #38241

Issue #32481 was closed as resolved after applying this fix.
Confirmed working by @AmerSarhan on Windows 11 Pro 25H2 Build 26200.

Currently there is zero documentation for these errors — users have no way to troubleshoot Cowork on Windows without searching through dozens of GitHub issues.