Cowork will not start

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?

Cowork fails to start on Windows 11 Pro with a Microsoft Store install. The CoworkVMService starts, successfully loads HCS/Hyper-V DLLs, but immediately crashes with a signature verification error.

Error shown in Cowork UI:

Failed to start Claude's workspace — VM service not running. The service failed to start.

Error from cowork-service.log:

Service error: signature verification initialization failed: failed to get service executable path: The system cannot find the path specified.

WHAT I'VE TRIED:

• Restarted Claude Desktop multiple times
• Rebooted computer
• Cleared cache via Help > Troubleshooting
• Manually deleted and reinstalled the VM bundle
• Attempted Start-Service -Name CoworkVMService as Administrator — fails
• Confirmed the executable exists at the registered path (Test-Path returns True)
• Confirmed service PathName matches the actual executable location
• Attempted icacls to grant SYSTEM read/execute access — blocked with "Access is denied" even as Administrator, due to Microsoft Store package sandboxing

What Should Happen?

Cowork should start successfully and the VM workspace should be available.

Error Messages/Logs

From `C:\ProgramData\Claude\Logs\cowork-service.log`:


2026/03/26 12:57:16 [HCS] Initializing HCS DLLs...
2026/03/26 12:57:16 Warning: failed to open service for recovery config: Access is denied.
2026/03/26 12:57:16 [HCS] vmcompute.dll loaded successfully
2026/03/26 12:57:16 [HCS] computecore.dll loaded successfully
2026/03/26 12:57:16 [HCS] Procs initialized, HCS ready
2026/03/26 12:57:16 [HCN] Initialized HCN API from computenetwork.dll
2026/03/26 12:57:16 [HCN] EnumerateNetworks result: ["c08cb7b8-9b3c-408e-8e30-5e16a3aeb444"]
2026/03/26 12:57:16 Service error: signature verification initialization failed: failed to get service executable path: The system cannot find the path specified.


## Root Cause Assessment

The CoworkVMService runs as SYSTEM and attempts to verify its own executable signature at startup. However, the Microsoft Store package sandbox restricts access to the WindowsApps folder — even the SYSTEM account cannot traverse it, as confirmed by `icacls` returning "Access is denied" even when run as Administrator. This appears to be a conflict between how the service performs signature verification and the permissions model enforced by MSIX/Store packages.

Steps to Reproduce

1. Install Claude Desktop via Microsoft Store on Windows 11 Pro
2. Open Cowork
3. Observe "VM service not running" error

Claude Model

Opus

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

Cowork

Platform

Other

Operating System

Windows

Terminal/Shell

Other

Additional Information

_No response_