[BUG] Cowork Windows - EPERM: operation not permitted, rename rootfs.vhdx

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?

What's Wrong?
Cowork workspace fails to start with:
"EPERM: operation not permitted, rename 'C:\Users\user\AppData\Local\Temp\wvm-XXXXX\rootfs.vhdx' -> 'C:\Users\user\AppData\Roaming\Claude\vm_bundles\claudevm.bundle\rootfs.vhdx'"

The rootfs.vhdx file in vm_bundles is permanently locked by another process. Cannot be deleted, renamed, or overwritten even after:

• Stopping Claude Desktop
• Stopping vmcompute and vmms services
• Stopping CoworkVMService
• Rebooting PC
• Deleting and reinstalling the workspace

The file lock persists across reboots, suggesting a system-level handle (possibly Hyper-V or antivirus).

Environment

• OS: Windows 11 Pro 25H2 (Build 26200.7840)
• Claude Desktop: v1.1.2685.0
• Hyper-V: Enabled
• Other software: ExpressVPN, Tailscale (both disabled during testing)
• Windows Defender: Active with exclusions added for Claude directories

Previously also hit the API unreachable/DNS issue (#25088, #25144) before this EPERM started occurring.

What Should Happen?

Cowork workspace should start successfully. The rootfs.vhdx file should be
renamed/moved from the temp directory to vm_bundles without permission errors.

Error Messages/Logs

EPERM: operation not permitted, rename 
'C:\Users\*user*\AppData\Local\Temp\wvm-XXXXX\rootfs.vhdx' -> 
'C:\Users\*user*\AppData\Roaming\Claude\vm_bundles\claudevm.bundle\rootfs.vhdx'

File remains locked even after stopping Claude, vmcompute, vmms, 
and CoworkVMService. Lock persists across reboots.

Steps to Reproduce

1. Install Claude Desktop v1.1.2685.0 on Windows 11 Pro
2. Enable Hyper-V
3. Switch to Cowork tab
4. Workspace download completes but fails on rootfs.vhdx rename
5. Click "reinstall the workspace" — same error
6. Manually stopping all services and attempting to delete/copy the file fails

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

1.1.2685.0 (Claude Desktop)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_