[BUG] CoworkVMService fails to start - signature verification error (Windows 11)

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?

OS: Windows 11
Installation: MSIX (via claude.ai/download)
Error: VM service not running. The service failed to start.

Event log shows:
"signature verification initialization failed:
failed to get service executable path:
The system cannot find the path specified"

Hyper-V is enabled (vmcompute and vmms both Running).
VM bundle exists and is complete (rootfs.vhdx, initrd, vmlinuz all present).
Tried: reinstall via .exe, reinstall via MSIX directly - same result every time.
Related issue: #29941

What Should Happen?

Cowork workspace should start successfully. The CoworkVMService should run and the VM should boot without errors.

Error Messages/Logs

Event log (Application, Source: CoworkVMService):
"signature verification initialization failed: failed to get service executable path: The system cannot find the path specified"

CoworkVMService Status: Stopped (StartType: Automatic)
VM bundle: complete (rootfs.vhdx, initrd, vmlinuz all present)
Hyper-V: vmcompute Running, vmms Running
Installation type: MSIX (via claude.ai/download and via direct MSIX)

Steps to Reproduce

1. Install Claude Desktop on Windows 11 via claude.ai/download (MSIX)
2. Open Claude Desktop
3. Click on Cowork tab
4. Error appears: "Failed to start Claude's workspace - VM service not running"
5. Checked Windows Event Log - signature verification error found
6. Tried: reinstall via .exe, reinstall via direct MSIX package - same result

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

Claude Desktop 1.1.7714.0

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_