Bug Report: CoworkVMService blocks MSIX update on Project Server (Claude Desktop 2.2553.1.0)

Preflight Checklist

• I have searched existing issues and this hasn't been reported yet
• This is a single bug report (please file separate reports for different bugs)
• I am using the latest version of Claude Code

What's Wrong?

Claude Desktop (2.2553.1.0, MSIX package) no longer launches, and the in-place
update cannot complete. The update fails with:

"C:\Program Files\WindowsApps\Claude_2.2553.1.0_x64__pzs8sxrjxfjjc..."
"Another program is currently using this file."

The lock is held by the service CoworkVMService (display name "Claude", binary:
app\resources\cowork-svc.exe), which keeps an open file handle on
C:\ProgramData\Claude\Logs\cowork-service.log (verified via Resource Monitor >
Associated Handles).

The service runs in Session 0 with StartMode = Auto. Stop-Service succeeds, but
the service restarts within seconds and re-acquires the lock before the updater
can replace the package files. Set-Service -StartupType Disabled fails with
"Access is denied" because the service is MSIX-packaged and cannot be
reconfigured.

I have tried every option available without rebooting:

• Stopping the service (Stop-Service -Force): it restarts within seconds
• Disabling the service (Set-Service -StartupType Disabled): "Access is denied"
• Killing all cowork-svc / Claude processes: they respawn automatically
• Microsoft Store update and Repair: still blocked by the file lock
• App Settings > Advanced options > Repair / Reset: no effect

Nothing resolves the issue. Every path ends at the same requirement: a full
machine reboot. This is a production server hosting multiple business-critical
applications that must run continuously, so rebooting during operations is not
an option.

What Should Happen?

The update should complete without requiring a reboot.

Specifically:

1. The installer should stop CoworkVMService before replacing package files,
   and restart it afterwards.
2. The service should not hold an exclusive handle on its own log file — it
   should be opened with FILE_SHARE_DELETE / FILE_SHARE_WRITE so it never
   blocks an update.
3. There should be a supported way to stop or disable the service without a
   reboot, for always-on servers where downtime is not acceptable.

Error Messages/Logs

Steps to Reproduce

Environment:

• Windows Server (production host running multiple business applications;
  continuous uptime required, reboot not possible during operations)
• Claude Desktop 2.2553.1.0, installed as MSIX package from WindowsApps
• Service: CoworkVMService ("Claude"), StartMode = Auto, Session 0

Steps:

1. Install Claude Desktop on Windows Server and let CoworkVMService start.

2. Leave the machine running so the service writes to
   C:\ProgramData\Claude\Logs\cowork-service.log

3. Trigger an app update (Microsoft Store > Library > Get updates), or let the
   automatic update run.

4. The update fails with "Another program is currently using this file."
   pointing at the WindowsApps package path.

5. Confirm the lock:

   • Resource Monitor > CPU > Associated Handles > search "claude"
   • Result: cowork-svc.exe holds a handle on
     C:\ProgramData\Claude\Logs\cowork-service.log

6. Identify the service:
   Get-CimInstance Win32_Service | Where-Object { $_.PathName -like "cowork" }
   -> Name: CoworkVMService, State: Running, StartMode: Auto

7. Attempt to release the lock:
   Stop-Service -Name CoworkVMService -Force
   -> succeeds; all cowork-svc / Claude processes disappear

   Set-Service -Name CoworkVMService -StartupType Disabled
   -> fails: "Access is denied"

8. Within seconds, cowork-svc.exe reappears with a new PID in Session 0 and
   re-acquires the file handle.

9. Retrying the update, Store "Repair", and app relaunch all fail identically.

10. Result: the application will not start, the update cannot be applied, and
    the only known fix (reboot) is not possible on this host.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

No response

Claude Code Version

2.2553.10

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

No response

No repository files or tests are named. Start by reproducing the update failure on Windows Server and inspect CoworkVMService/cowork-svc.exe with the listed PowerShell commands and Resource Monitor; done means the MSIX update completes without a reboot while the service can be stopped and restarted without retaining the blocking handle.