[BUG] CoworkVMService crashes with "signature verification initialization failed" — Windows 11 Pro 25H2

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?

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported with this exact log
• [x] This is a single bug report
• [x] I am using the latest version of Claude Desktop

Environment

• OS: Windows 11 Pro — Version 25H2
• Claude Desktop: Latest version
• Subscription: Max plan
• Hyper-V: Enabled
• Virtual Machine Platform: Enabled
• Windows Hypervisor Platform: Enabled

What's Wrong?

Cowork is permanently stuck on "Starting session...".
No error message is displayed in the UI. No session ever starts.

The issue has been reproducible consistently since 2026-03-12
and persists across all troubleshooting attempts listed below.

Error in Logs (cowork_vm_node.log)

The following two errors appear on every single start attempt:

What Should Happen?

The HCS/HCN DLLs load successfully every time
(vmcompute.dll, computecore.dll, computenetwork.dll),
but the service crashes immediately after during signature verification,
before any network or VM operations occur.

Steps to Reproduce

1. Install Claude Desktop (latest) on Windows 11 Pro 25H2
2. Ensure Hyper-V, Virtual Machine Platform,

and Windows Hypervisor Platform are all enabled

1. Open Claude Desktop and navigate to the Cowork tab
2. Observe: UI stays stuck on "Starting session..." indefinitely

Troubleshooting Already Attempted (all failed)

1. Checked internet connection — working fine, regular Chat mode works perfectly
2. Closed and relaunched the session
3. Updated Claude Desktop to latest version
4. Full app restart
5. Full computer reboot
6. Manual service start via PowerShell (admin):

Start-Service CoworkVMService → fails with StartServiceFailed

1. Verified all Windows virtualization features are enabled
2. Used debug menu: "Delete Cowork VM bundle and restart"

Expected Behavior

Cowork workspace should start successfully and become usable.

Related Issues

This appears to be the same root cause as:

• #29941 — signature verification initialization failed (Win 11 Pro)
• #32481 — CoworkVMService crashes "Incorrect function" (Win 11 Pro 25H2)
• #38063 — CoworkVMService crashes ERROR_INVALID_FUNCTION (Win 11 Pro 25H2)
• #38396 — CoworkVMService ExitCode 1066 (Win 11 Pro 25H2)

The service binary (cowork-svc.exe) appears unable to resolve
its own executable path from within the MSIX/WindowsApps package context,
despite the file existing and being validly signed.
No user-side fix is available for this issue.

Error Messages/Logs

## Full Log
<details>
<summary>cowork_vm_node.log</summary>

[colle le log ici]

</details>

Steps to Reproduce

1. Install Claude Desktop (latest version) on Windows 11 Pro 25H2
2. Enable Hyper-V, Virtual Machine Platform, and Windows Hypervisor Platform in Windows Features
3. Open Claude Desktop
4. Click on the Cowork tab
5. Observe: UI stays stuck on "Starting session..." indefinitely, no error message displayed

No specific code or files required to reproduce — the issue occurs on every startup attempt.

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

Version 1.1.9493 (b58a0b)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

cowork-service.log