[BUG] [Cowork] Windows: EXDEV error on rename during VM bundle setup (EFS-related)

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?

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report
• [x] I am using the latest version of Claude Code

What's Wrong?

Cowork workspace setup fails on Windows 11 with an EXDEV: cross-device link not permitted error when the app tries to rename() downloaded files from %TEMP% to the vm_bundles directory.

The root cause appears to be EFS (Encrypting File System) interaction with Node.js fs.rename(). The system has a corporate environment where EFS encrypts files in WindowsApps and AppData. Even after:

• Disabling EFS via registry (HKLM\SOFTWARE\Policies\Microsoft\Windows\EFS\EfsConfiguration = 1)
• Decrypting the destination folder with cipher /d
• Reinstalling the app
• Redirecting TEMP to the same parent folder as the destination

The rename() call still fails with EXDEV, even when both source and destination are on the same drive (C:) and same filesystem.

Error Message

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

This also affects smol-bin.vhdx which is EFS-encrypted inside WindowsApps:

UNKNOWN: unknown error, copyfile 
'C:\Program Files\WindowsApps\Claude_1.1.3189.0_x64__pzs8sxrjxfjjc\app\resources\smol-bin.x64.vhdx' -> 
'C:\Users\<user>\AppData\Roaming\Claude\vm_bundles\claudevm.bundle\smol-bin.vhdx'

Environment

• Claude Desktop version: 1.1.3189.0 (MSIX)
• OS: Windows 11 Pro (corporate managed)
• EFS: Active on WindowsApps directory (corporate policy)
• Hyper-V: Enabled

Suggested Fix

The app should use fs.copyFile() + fs.unlink() as a fallback when fs.rename() fails with EXDEV, similar to how tools like mv handle cross-device moves. The copyfile operation for smol-bin.vhdx should also handle EFS-encrypted source files (e.g., using raw copy mode).

Related Issues

• #24962 - Cowork VM fails on Windows 11 Home
• #24974 - sessiondata.vhdx not created + macOS diagnostics on Windows
• #25474 - Cowork VM never creates on Windows

What Should Happen?

Claude Cowork doesn't work in Windows 11

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report
• [x] I am using the latest version of Claude Code

What's Wrong?

Cowork workspace setup fails on Windows 11 with an EXDEV: cross-device link not permitted error when the app tries to rename() downloaded files from %TEMP% to the vm_bundles directory.

The root cause appears to be EFS (Encrypting File System) interaction with Node.js fs.rename(). The system has a corporate environment where EFS encrypts files in WindowsApps and AppData. Even after:

• Disabling EFS via registry (HKLM\SOFTWARE\Policies\Microsoft\Windows\EFS\EfsConfiguration = 1)
• Decrypting the destination folder with cipher /d
• Reinstalling the app
• Redirecting TEMP to the same parent folder as the destination

The rename() call still fails with EXDEV, even when both source and destination are on the same drive (C:) and same filesystem.

Error Message

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

This also affects smol-bin.vhdx which is EFS-encrypted inside WindowsApps:

UNKNOWN: unknown error, copyfile 
'C:\Program Files\WindowsApps\Claude_1.1.3189.0_x64__pzs8sxrjxfjjc\app\resources\smol-bin.x64.vhdx' -> 
'C:\Users\<user>\AppData\Roaming\Claude\vm_bundles\claudevm.bundle\smol-bin.vhdx'

Environment

• Claude Desktop version: 1.1.3189.0 (MSIX)
• OS: Windows 11 Pro (corporate managed)
• EFS: Active on WindowsApps directory (corporate policy)
• Hyper-V: Enabled

Suggested Fix

The app should use fs.copyFile() + fs.unlink() as a fallback when fs.rename() fails with EXDEV, similar to how tools like mv handle cross-device moves. The copyfile operation for smol-bin.vhdx should also handle EFS-encrypted source files (e.g., using raw copy mode).

Related Issues

• #24962 - Cowork VM fails on Windows 11 Home
• #24974 - sessiondata.vhdx not created + macOS diagnostics on Windows
• #25474 - Cowork VM never creates on Windows

Error Messages/Logs

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


This also affects `smol-bin.vhdx` which is EFS-encrypted inside WindowsApps:

UNKNOWN: unknown error, copyfile 
'C:\Program Files\WindowsApps\Claude_1.1.3189.0_x64__pzs8sxrjxfjjc\app\resources\smol-bin.x64.vhdx' -> 
'C:\Users\<user>\AppData\Roaming\Claude\vm_bundles\claudevm.bundle\smol-bin.vhdx'


## Environment

- **Claude Desktop version:** 1.1.3189.0 (MSIX)
- **OS:** Windows 11 Pro (corporate managed)
- **EFS:** Active on WindowsApps directory (corporate policy)
- **Hyper-V:** Enabled

## Suggested Fix

The app should use `fs.copyFile()` + `fs.unlink()` as a fallback when `fs.rename()` fails with `EXDEV`, similar to how tools like `mv` handle cross-device moves. The `copyfile` operation for `smol-bin.vhdx` should also handle EFS-encrypted source files (e.g., using raw copy mode).

## Related Issues

- #24962 - Cowork VM fails on Windows 11 Home
- #24974 - sessiondata.vhdx not created + macOS diagnostics on Windows
- #25474 - Cowork VM never creates on Windows

Steps to Reproduce

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report
• [x] I am using the latest version of Claude Code

What's Wrong?

Cowork workspace setup fails on Windows 11 with an EXDEV: cross-device link not permitted error when the app tries to rename() downloaded files from %TEMP% to the vm_bundles directory.

The root cause appears to be EFS (Encrypting File System) interaction with Node.js fs.rename(). The system has a corporate environment where EFS encrypts files in WindowsApps and AppData. Even after:

• Disabling EFS via registry (HKLM\SOFTWARE\Policies\Microsoft\Windows\EFS\EfsConfiguration = 1)
• Decrypting the destination folder with cipher /d
• Reinstalling the app
• Redirecting TEMP to the same parent folder as the destination

The rename() call still fails with EXDEV, even when both source and destination are on the same drive (C:) and same filesystem.

Error Message

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

This also affects smol-bin.vhdx which is EFS-encrypted inside WindowsApps:

UNKNOWN: unknown error, copyfile 
'C:\Program Files\WindowsApps\Claude_1.1.3189.0_x64__pzs8sxrjxfjjc\app\resources\smol-bin.x64.vhdx' -> 
'C:\Users\<user>\AppData\Roaming\Claude\vm_bundles\claudevm.bundle\smol-bin.vhdx'

Environment

• Claude Desktop version: 1.1.3189.0 (MSIX)
• OS: Windows 11 Pro (corporate managed)
• EFS: Active on WindowsApps directory (corporate policy)
• Hyper-V: Enabled

Suggested Fix

The app should use fs.copyFile() + fs.unlink() as a fallback when fs.rename() fails with EXDEV, similar to how tools like mv handle cross-device moves. The copyfile operation for smol-bin.vhdx should also handle EFS-encrypted source files (e.g., using raw copy mode).

Related Issues

• #24962 - Cowork VM fails on Windows 11 Home
• #24974 - sessiondata.vhdx not created + macOS diagnostics on Windows
• #25474 - Cowork VM never creates on Windows

Claude Model

Opus

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

• Claude Desktop version: 1.1.3189.0 (MSIX)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report
• [x] I am using the latest version of Claude Code

What's Wrong?

Cowork workspace setup fails on Windows 11 with an EXDEV: cross-device link not permitted error when the app tries to rename() downloaded files from %TEMP% to the vm_bundles directory.

The root cause appears to be EFS (Encrypting File System) interaction with Node.js fs.rename(). The system has a corporate environment where EFS encrypts files in WindowsApps and AppData. Even after:

• Disabling EFS via registry (HKLM\SOFTWARE\Policies\Microsoft\Windows\EFS\EfsConfiguration = 1)
• Decrypting the destination folder with cipher /d
• Reinstalling the app
• Redirecting TEMP to the same parent folder as the destination

The rename() call still fails with EXDEV, even when both source and destination are on the same drive (C:) and same filesystem.

Error Message

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

This also affects smol-bin.vhdx which is EFS-encrypted inside WindowsApps:

UNKNOWN: unknown error, copyfile 
'C:\Program Files\WindowsApps\Claude_1.1.3189.0_x64__pzs8sxrjxfjjc\app\resources\smol-bin.x64.vhdx' -> 
'C:\Users\<user>\AppData\Roaming\Claude\vm_bundles\claudevm.bundle\smol-bin.vhdx'

Environment

• Claude Desktop version: 1.1.3189.0 (MSIX)
• OS: Windows 11 Pro (corporate managed)
• EFS: Active on WindowsApps directory (corporate policy)
• Hyper-V: Enabled

Suggested Fix

The app should use fs.copyFile() + fs.unlink() as a fallback when fs.rename() fails with EXDEV, similar to how tools like mv handle cross-device moves. The copyfile operation for smol-bin.vhdx should also handle EFS-encrypted source files (e.g., using raw copy mode).

Related Issues

• #24962 - Cowork VM fails on Windows 11 Home
• #24974 - sessiondata.vhdx not created + macOS diagnostics on Windows
• #25474 - Cowork VM never creates on Windows