[BUG] Cowork: "Virtualization not available" — VM service not responding, no logs generated (Windows 11 Pro)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Environment

• OS: Windows 11 Pro
• Claude Desktop version: 1.2278.0.0
• Installation type: Microsoft Store (MSIX package)

What's Wrong?

Cowork fails to start with the error: "Virtualization is not available. Claude's workspace requires Virtual Machine Platform, but the virtualization service is not responding. Restart your computer to fix the issue."

Restarting does not fix the issue. Reinstalling Claude Desktop does not fix the issue.

Prerequisites verified (all met)

• Hyper-V: Enabled
• VirtualMachinePlatform: Enabled
• HypervisorPlatform: Enabled
• vmms service: Running (Automatic)
• HvHost service: Running (Manual, started manually)
• CoworkVMService: Running
• hcsdiag list: returns empty — VM never starts

Troubleshooting attempted

1. Restarted PC multiple times
2. Re-enabled all Hyper-V features via PowerShell (Enable-WindowsOptionalFeature)
3. Full clean uninstall + reinstall of Claude Desktop (including manual removal of all AppData folders)
4. Manually started HvHost and CoworkVMService
5. Reinstalled workspace from within Cowork UI

None of the above resolved the issue.

Additional observations

• After a clean reinstall, no logs are generated in %LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\logs\ — the folder doesn't even exist
• vm_bundles and claude-code-vm directories are never created
• Cowork appears to fail before even attempting to initialize the VM

Expected behavior
Cowork should start the VM and make the workspace available.

Actual behavior
Cowork immediately shows "Virtualization is not available" without generating any diagnostic logs.

What Should Happen?

<img width="1190" height="686" alt="Image" src="https://github.com/user-attachments/assets/8d0d8624-12e5-441e-b9ad-877995f1d17d" />

Error Messages/Logs

Steps to Reproduce

Cowork immediately shows "Virtualization is not available" without generating any diagnostic logs.

Claude Model

Not sure / Multiple models

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

1.2278.0.0

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

<img width="1190" height="686" alt="Image" src="https://github.com/user-attachments/assets/ecfa4e37-f4ca-4969-bfda-6d69ab4e919f" />