[BUG] Cowork/Workspace EXDEV: cross-device link not permitted on Windows 11 — rootfs.vhdx rename fails

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?

Claude Desktop Workspace/Cowork feature fails to start on Windows 11 with the following error every time:

EXDEV: cross-device link not permitted, rename 'C:\Users\nitro\AppData\Roaming\Claude\vm_bundles\claudevm.bundle\.wvm-tmp-XXXXXX\rootfs.vhdx' -> 'C:\Users\nitro\AppData\Roaming\Claude\vm_bundles\claudevm.bundle\rootfs.vhdx'

Environment

• Claude Desktop version: Latest (.exe from claude.ai/download)
• OS: Windows 11
• Install type: Non-MSIX direct .exe installer
• Hyper-V: Enabled

Steps to Reproduce

1. Install Claude Desktop on Windows 11
2. Open Claude Desktop
3. Click Workspace/Cowork tab
4. Observe error immediately

What I Tried

• Clean reinstall (multiple times, including deleting AppData\Roaming\Claude)
• Resetting TEMP/TMP environment variables to default
• Disabling OneDrive, Dropbox, Google Drive
• Manual file copy via PowerShell
• Nothing worked

Expected Behavior

Workspace should download and initialize rootfs.vhdx successfully.

Additional Notes

This is a known bug reported since February 2026 (issues #25476, #30584, #36642, #37094, #38030, #38457, #39029). The root cause is that fs.rename() fails across filesystem boundaries on Windows. The fix should be to use fs.copyFile() + fs.unlink() as a fallback when EXDEV is encountered.

Please prioritize this fix as the Workspace feature is completely unusable on Windows for many users.

<img width="1919" height="1079" alt="Image" src="https://github.com/user-attachments/assets/399f3745-81ef-4a2a-9300-3d42567dece0" />

What Should Happen?

Workspace should download rootfs.vhdx and initialize successfully without EXDEV errors.

Error Messages/Logs

EXDEV: cross-device link not permitted, rename 'C:\Users\nitro\AppData\Roaming\Claude\vm_bundles\claudevm.bundle\.wvm-tmp-boqyjb\rootfs.vhdx' -> 'C:\Users\nitro\AppData\Roaming\Claude\vm_bundles\claudevm.bundle\rootfs.vhdx'

Steps to Reproduce

1. Install Claude Desktop on Windows 11 (.exe from claude.ai/download)
2. Open Claude Desktop
3. Click Workspace/Cowork tab
4. Observe EXDEV error immediately — feature never works

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

N/A

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

This is a known bug reported since February 2026. Related issues: #25476, #30584, #36642, #37094, #38030, #38457, #39029

Root cause: fs.rename() fails across filesystem boundaries on Windows. The fix should be to use fs.copyFile() + fs.unlink() as a fallback when EXDEV is encountered.

I have tried: clean reinstall, clearing AppData, resetting TEMP/TMP variables, disabling OneDrive/Dropbox/Google Drive, manual PowerShell copy. Nothing worked.

<img width="1919" height="1079" alt="Image" src="https://github.com/user-attachments/assets/28897953-e62b-4a19-8a4a-07d1b3114a39" />