[BUG] CoworkVMService fails with "signature verification initialization failed" when MSIX is installed on non-system volume (D: drive)

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 immediately crashes with exit code 1 ("Incorrect function") when the Claude MSIX package is physically stored on a non-C: volume (e.g., D:). The Cowork tab appears stuck loading and the VM never boots.When Windows installs the MSIX to a secondary volume (D:\WindowsApps), the service binary path shows as C:\Program Files\WindowsApps... (the standard mount point). During startup, cowork-svc.exe tries to resolve its own executable path for signature verification and fails because the path doesn't resolve as expected from the D: physical location.The Hyper-V compute stack initializes successfully — vmcompute.dll, computecore.dll, and HCN all load fine. The service aborts at the signature verification step before ever attempting to start the VM.This may be the root cause for multiple other Cowork failures reported in #25136, #32004, #27316, #27420, #29887, and #32233. Users experiencing those issues should check whether their MSIX installed to a non-C: volume with Test-Path "D:\WindowsApps\Claude_*" (or their secondary drive letter).

What Should Happen?

CoworkVMService should start successfully and boot the VM regardless of which volume the MSIX package is installed on. The signature verification path resolution should handle the WindowsApps mount point / volume redirection correctly.

Error Messages/Logs

From C:\ProgramData\Claude\Logs\cowork-service.log:
2026/03/21 10:01:26.452939 Starting CoworkVMService as Windows service
2026/03/21 10:01:26.452939 Claude VM Service starting...
2026/03/21 10:01:26.452939 Waiting for configuration from app via 'configure' method...
2026/03/21 10:01:26.452939 [HCS] Initializing HCS DLLs...
2026/03/21 10:01:26.459608 Warning: failed to open service for recovery config: Access is denied.
2026/03/21 10:01:26.465979 [HCS] vmcompute.dll loaded successfully
2026/03/21 10:01:26.466511 [HCS] computecore.dll loaded successfully
2026/03/21 10:01:26.466511 [HCS] Procs initialized, HCS ready
2026/03/21 10:01:26.467041 [HCN] Initialized HCN API from computenetwork.dll
2026/03/21 10:01:30.913409 [HCN] EnumerateNetworks result: []
2026/03/21 10:01:30.918677 Service error: signature verification initialization failed: failed to get service executable path: The system cannot find the path specified.
Windows System event log:
The Claude service terminated with the following service-specific error: Incorrect function.
sc query CoworkVMService shows WIN32_EXIT_CODE: 1066 (0x42a), SERVICE_EXIT_CODE: 1 (0x1).
Environment:

Claude Desktop: v1.1.7714.0
OS: Windows 11 Pro 25H2 (Build 26200)
Hyper-V, VirtualMachinePlatform, HypervisorPlatform: all Enabled
Default app install volume: D:

Steps to Reproduce

Set default app install location to a non-C: drive (Settings → System → Storage → Where new content is saved → D:)
Install Claude Desktop from claude.ai/download
Verify package is physically on D: (Test-Path "D:\WindowsApps\Claude_*" returns True)
Open Claude Desktop and navigate to the Cowork tab
Observe Cowork stuck loading
Check C:\ProgramData\Claude\Logs\cowork-service.log for the signature verification error

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude Desktop version: 1.1.7714.0

Platform

Other

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Workaround:

Uninstall Claude: Get-AppxPackage -Name "Claude" | Remove-AppxPackage
Clean up leftover files: Remove-Item "D:\WindowsApps\Claude_*" -Recurse -Force
Change default app install location to C: (Settings → System → Storage)
Reinstall Claude from claude.ai/download
Optionally change default install location back to D:

After reinstalling to C:, CoworkVMService starts successfully and the VM boots normally. The cowork-service.log confirms: [VM] VM started successfully

Related issues where the root cause may also be non-C: installation: #25136, #32004, #25055