[BUG] Cowork: "VM service not running" — signature verification fails to resolve service executable path (Win11 Pro 24H2, v1.1.8359.0)

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?

CoworkVMService starts, successfully loads HCS and HCN DLLs, then immediately crashes with exit code 1066 due to a signature verification failure. The service cannot resolve its own executable path from within the MSIX container.

Key error from C:\ProgramData\Claude\Logs\cowork-service.log:

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

This occurs every startup attempt. The service never reaches VM creation — it crashes during its own initialisation sequence.

Environment:

• OS: Windows 11 Pro (10.0.26200), 24H2
• Claude Desktop: v1.1.8359.0
• MSIX Package: Claude_1.1.8359.0_x64__pzs8sxrjxfjjc (SignatureKind: Developer)
• Hyper-V: Enabled, vmms Running/Automatic
• HCS (vmcompute): Running
• Single Claude version installed (no stale versions in WindowsApps)
• Service exe exists: C:\Program Files\WindowsApps\Claude_1.1.8359.0_x64__pzs8sxrjxfjjc\app\resources\cowork-svc.exe — verified via Test-Path (True)

What Should Happen?

CoworkVMService should successfully complete its initialisation sequence, resolve its own executable path within the MSIX container, pass signature verification, and proceed to create the VM. The "Cowork" workspace should launch without errors.

Error Messages/Logs

### cowork-service.log (full startup sequence)

2026/03/24 13:13:41.994715 Starting CoworkVMService as Windows service
2026/03/24 13:13:41.997955 Claude VM Service starting...
2026/03/24 13:13:41.997955 Waiting for configuration from app via 'configure' method...
2026/03/24 13:13:41.997955 [HCS] Initializing HCS DLLs...
2026/03/24 13:13:41.998479 Warning: failed to open service for recovery config: Access is denied.
2026/03/24 13:13:42.001104 [HCS] vmcompute.dll loaded successfully
2026/03/24 13:13:42.002156 [HCS] computecore.dll loaded successfully
2026/03/24 13:13:42.002156 [HCS] Procs initialized, HCS ready
2026/03/24 13:13:42.002156 [HCN] Initialized HCN API from computenetwork.dll
2026/03/24 13:13:42.007578 [HCN] EnumerateNetworks result: ["c08cb7b8-9b3c-408e-8e30-5e16a3aeb444"]
2026/03/24 13:13:42.013840 Service error: signature verification initialization failed: failed to get service executable path: The system cannot find the path specified.

### Service Control Manager (System Event Log, ID 7024)

The Claude service terminated with the following service-specific error: Incorrect function.

### cowork_vm_node.log

2026-03-24 13:02:37 [info] [VM:start] Configuring Windows VM service...
2026-03-24 13:02:42 [error] [VM:start] Startup failed: Error: VM service not running. The service failed to start.

### Service registration

PathName : "C:\Program Files\WindowsApps\Claude_1.1.8359.0_x64__pzs8sxrjxfjjc\app\resources\cowork-svc.exe"
State    : Stopped
ExitCode : 1066

### MSIX Package (PowerShell)

Get-AppxPackage -Name "Claude" | Select Name, Version, InstallLocation, Status, SignatureKind

Name            : Claude
Version         : 1.1.8359.0
InstallLocation : C:\Program Files\WindowsApps\Claude_1.1.8359.0_x64__pzs8sxrjxfjjc
Status          : Ok
SignatureKind   : Developer

Steps to Reproduce

1. Open Claude Desktop v1.1.8359.0 on Windows 11 Pro 24H2
2. Click Cowork
3. Observe error: "Failed to start Claude's workspace — VM service not running. The service failed to start."
4. Error persists after full reboot, workspace reinstall, and MSIX package re-registration

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

v1.1.8359.0

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Root Cause Analysis

The service binary (cowork-svc.exe) attempts to verify its own signature during initialisation. The path resolution step fails with "The system cannot find the path specified" despite the executable clearly existing at the registered path. This appears to be an MSIX container path resolution issue within the service binary itself — all Windows-side prerequisites (Hyper-V, HCS, HCN, permissions) are functional.

The cowork-service.log shows HCS and HCN initialise successfully before the signature check fails, confirming the issue is not with Hyper-V or networking.

Troubleshooting Attempted (all failed)

• Full Windows reboot
• Reinstall workspace from Cowork UI
• Re-registered MSIX package via Add-AppxPackage -Register ... -DisableDevelopmentMode
• Manually created HNS network and WinNAT rule (service deletes the network on startup then crashes anyway — logs it as "Removing legacy HCN network")
• Created missing sessiondata.vhdx manually via New-VHD
• Confirmed no DCOM 10016 errors related to Claude (only Windows Security Center)
• Confirmed single Claude version installed (no stale WindowsApps entries)

Additional Side-Effect

When Cowork fails, the Windows shell becomes unresponsive — desktop icons and taskbar items stop responding until Claude is force-closed. This suggests the service failure may be holding a system resource or lock.

Related Issues

• #36801 — Exit code 1066, same log pattern (no logging beyond module load)
• #27801 — VM service not running regression from v1.1.3189
• #30179 — DCOM blocks CoworkVMService (different root cause)
• #25206 — VM starts then crashes within 5 minutes