### Preflight Checklist - [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) 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 lat

[BUG] Cowork fails on Windows when WindowsApps is on non-C:\ drive and AppData has EFS encryption enforced by group policy

Open 💬 0 comments Opened Jul 13, 2026 by Derkdv

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 Desktop

---

What's Wrong?

Cowork is completely non-functional on Windows when:

The Windows Apps / MSIX container is installed on a non-C:\ drive (D:\), AND
C:\AppData\Roaming has EFS (Encrypting File System) enabled via group policy

This combination causes all Cowork file operations to fail because Claude's MSIX process writes to D:\ but then attempts to rename/move files to C:\AppData\Roaming\Claude\, which is EFS-encrypted. The process does not hold the EFS certificate and cannot write there.

---

Errors Observed (in order of troubleshooting)

Initial error:

Failed to start Claude's workspace
EXDEV: cross-device link not permitted, rename 'C:\Users\derkd\AppData\Roaming\Claude\vm_bundles\claudevm.bundle\rootfs.vhdx.zst.21237ca86d15.partial' -> 'C:\Users\derkd\AppData\Roaming\Claude\vm_bundles\claudevm.bundle\rootfs.vhdx.zst'

After creating a junction from C:\AppData\Roaming\Claude\vm_bundles to D:\WpSystem\...\vm_bundles:

UNKNOWN: unknown error, scandir 'C:\Users\derkd\AppData\Roaming\Claude\vm_bundles\claudevm.bundle'

(The sandboxed MSIX process cannot traverse junctions to arbitrary locations)

When attempting to manually copy files to C:\AppData\Roaming\Claude\vm_bundles:

Copy-Item: Kan het opgegeven bestand niet versleutelen. (Cannot encrypt the specified file)

Same error with robocopy /EFSRAW — EFS is enforced at group policy level.

Additionally, scheduled tasks fail with:

Couldn't attach "SKILL.md": the file couldn't be copied from this location.

Same underlying EFS conflict affecting all Cowork file operations.

---

Root Cause Analysis

The MSIX container for Claude Desktop is installed on D:\ (D:\WpSystem\S-1-5-21-...\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\). Claude's VM service writes temp/partial files within this D:\ container, then attempts an atomic rename to C:\AppData\Roaming\Claude\vm_bundles\. This rename fails with EXDEV because:

The source is on D:\
The destination is on C:\ with EFS enforced by group policy
Claude's sandboxed process does not hold the EFS certificate

Note: C:\AppData\Roaming correctly resolves to C:\ (not redirected). The split is caused by WindowsApps being installed on D:\, which is a supported and common Windows configuration.

Evidence from cowork-service.log:

Early sessions (April 2026): vmcompute.dll failed to load entirely
From July 2, 2026: vmcompute.dll loads successfully, HCS ready — but file operations still fail due to EFS
claude.exe verified at: D:\WindowsApps\Claude_1.19367.0.0_x64__pzs8sxrjxfjjc\app\claude.exe
Session user: derkd, AppData at C:\Users\derkd\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude

---

Expected Behavior

Cowork should store the VM bundle (rootfs.vhdx.zst and related files) entirely within the MSIX container path on D:\ where the process already runs and has write access — rather than attempting to move files to C:\AppData\Roaming. Alternatively, Cowork should detect EFS on the target path and handle it gracefully, or document EFS as an unsupported configuration.

---

Environment

OS: Windows 11
Claude Desktop version: 1.19367.0.0
Windows Apps installed on: D:\
C:\AppData\Roaming: EFS-encrypted via group policy
User: derkd
Hyper-V / HCS: functional (vmcompute.dll loads successfully as of July 2026)

---

Workarounds Attempted (all failed)

Junction from C:\AppData\Roaming\Claude\vm_bundles → D:\WpSystem\...\vm_bundles: fails with scandir error (MSIX sandbox cannot traverse junctions)
Manual copy of bundle files to C:\ using Copy-Item: blocked by EFS
Manual copy using robocopy /EFSRAW: blocked by EFS group policy
Multiple clean reinstalls: same issue persists
cipher /d to disable EFS on Claude folder: EFS re-enforced by group policy

No manual workaround is available. This requires a fix in the [application.[](url)](url)

What Should Happen?

Normal behaviour, no error codes

cowork-service.log

Error Messages/Logs

Steps to Reproduce

2026/07/01 14:57:23.927075 [Server] Persistent RPC: connection ended: message too large: 2065853797 bytes
2026/07/01 14:57:25.520400 [Server] Session derkd:C:\Users\derkd\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude has no active connections, idle timeout starts
2026/07/01 14:57:26.601684 [Server] Client connected
2026/07/01 14:57:41.112504 [Server] Client signature verified: D:\WindowsApps\Claude_1.15962.1.0_x64__pzs8sxrjxfjjc\app\claude.exe (subject: Anthropic, PBC)
2026/07/01 14:57:41.172587 [Server] Client connected: user=derkd exe=claude.exe isDev=false
2026/07/01 14:57:41.304546 [Server] Persistent RPC: entering loop
2026/07/01 14:59:22.119927 [Server] Persistent RPC: connection ended: message too large: 2065853797 bytes
2026/07/01 14:59:22.542379 [Server] Session derkd:C:\Users\derkd\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude has no active connections, idle timeout starts
2026/07/01 14:59:25.385825 [Server] Client connected
2026/07/01 14:59:40.877382 [Server] Client signature verified: D:\WindowsApps\Claude_1.15962.1.0_x64__pzs8sxrjxfjjc\app\claude.exe (subject: Anthropic, PBC)
2026/07/01 14:59:40.938767 [Server] Client connected: user=derkd exe=claude.exe isDev=false
2026/07/01 14:59:41.279162 [Server] Persistent RPC: entering loop
2026/07/01 15:43:15.422527 [Server] Persistent RPC: connection ended: failed to read length: EOF
2026/07/01 15:43:15.490302 [Server] Session derkd:C:\Users\derkd\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude has no active connections, idle timeout starts
2026/07/01 15:43:29.739316 Service stop requested
2026/07/01 15:43:29.796509 Shutdown signal received...
2026/07/01 15:43:29.836080 [Server] Stopping server...
2026/07/01 15:43:29.878970 [Server] Stopping VM for session derkd:C:\Users\derkd\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude...
2026/07/01 15:43:29.887977 [VM] VM already stopped, nothing to release
2026/07/01 15:43:29.887977 [Server] Server stopped
2026/07/01 15:43:29.887977 Service stopped.
2026/07/01 15:44:44.384068 Starting CoworkVMService as Windows service
2026/07/01 15:44:46.366606 Claude VM Service starting...
2026/07/01 15:44:46.366606 Waiting for configuration from app via 'configure' method...
2026/07/01 15:44:46.378202 [HCS] Initializing HCS DLLs...
2026/07/01 15:44:46.374169 Warning: failed to open service for recovery config: Access is denied.
2026/07/01 15:44:46.899748 [HCS] vmcompute.dll loaded successfully
2026/07/01 15:44:47.193575 [HCS] computecore.dll loaded successfully
2026/07/01 15:44:47.193575 [HCS] Procs initialized, HCS ready
2026/07/01 15:44:47.204520 [HCN] Initialized HCN API from computenetwork.dll
2026/07/01 15:45:43.823296 Service stop requested
2026/07/01 15:46:13.823864 Timeout waiting for service to stop
2026/07/01 15:46:19.813183 Starting CoworkVMService as Windows service
2026/07/01 15:46:19.852213 Claude VM Service starting...
2026/07/01 15:46:19.852213 Waiting for configuration from app via 'configure' method...
2026/07/01 15:46:19.852213 [HCS] Initializing HCS DLLs...
2026/07/01 15:46:19.852742 Warning: failed to open service for recovery config: Access is denied.
2026/07/01 15:46:19.855493 [HCS] vmcompute.dll loaded successfully
2026/07/01 15:46:19.856622 [HCS] computecore.dll loaded successfully
2026/07/01 15:46:19.856622 [HCS] Procs initialized, HCS ready
2026/07/01 15:46:19.856622 [HCN] Initialized HCN API from computenetwork.dll
2026/07/01 15:49:23.322949 [HCN] EnumerateNetworks result: []
2026/07/01 15:49:25.186309 [Server] Signature verification initialized
2026/07/01 15:49:25.186309 [Server] Service: C:\Program Files\WindowsApps\Claude_1.17377.1.0_x64__pzs8sxrjxfjjc\app\resources\cowork-svc.exe
2026/07/01 15:49:25.186309 [Server] Subject: Anthropic, PBC
2026/07/01 15:49:25.186309 [Server] Thumbprint: dbde5d16768ed0c1...
2026/07/01 15:49:25.186309 [Server] Enforce: true
2026/07/01 15:49:25.186309 [Server] Starting named pipe server on \\.\pipe\cowork-vm-service
2026/07/01 15:49:25.187429 [Server] Named pipe server listening
2026/07/01 15:49:25.187429 Service ready. Listening on \\.\pipe\cowork-vm-service
2026/07/01 15:49:36.243127 [Server] Client connected
2026/07/01 15:50:09.304495 [Server] Client signature verified: D:\WindowsApps\Claude_1.17377.1.0_x64__pzs8sxrjxfjjc\app\claude.exe (subject: Anthropic, PBC)
2026/07/01 15:50:10.037182 [Server] Client connected: user=derkd exe=claude.exe isDev=false
2026/07/01 15:50:10.407643 [VM] VM owner set: id=cowork-vm-9d09517d sid=S-1-5-21-3673970679-1154737977-1649588588-1001
2026/07/01 15:50:10.407643 [VM] Event callbacks set
2026/07/01 15:50:10.407643 [Server] Created new VM session for derkd:C:\Users\derkd\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude
2026/07/01 15:50:10.409657 [Server] Persistent RPC: entering loop
2026/07/01 15:50:15.187837 [IdleCheck] Session derkd:C:\Users\derkd\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude: starting idle timer now
2026/07/02 09:58:43.624280 [Server] Persistent RPC: connection ended: failed to read length: EOF
2026/07/02 09:58:43.723411 [Server] Session derkd:C:\Users\derkd\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude has no active connections, idle timeout starts
2026/07/02 09:58:43.936849 Service stop requested
2026/07/02 09:58:43.946469 Shutdown signal received...
2026/07/02 09:58:43.947657 [Server] Stopping server...
2026/07/02 09:58:43.949244 [Server] Stopping VM for session derkd:C:\Users\derkd\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude...
2026/07/02 09:58:44.001111 [VM] VM already stopped, nothing to release
2026/07/02 09:58:44.001111 [Server] Server stopped
2026/07/02 09:58:44.001111 Service stopped.
2026/07/02 09:58:47.903921 Starting CoworkVMService as Windows service
2026/07/02 09:58:47.968295 Claude VM Service starting...
2026/07/02 09:58:47.968295 Waiting for configuration from app via 'configure' method...
2026/07/02 09:58:47.968295 [HCS] Initializing HCS DLLs...
2026/07/02 09:58:47.968803 Warning: failed to open service for recovery config: Access is denied.
2026/07/02 09:58:47.978053 [HCS] vmcompute.dll loaded successfully
2026/07/02 09:58:47.981916 [HCS] computecore.dll loaded successfully
2026/07/02 09:58:47.981916 [HCS] Procs initialized, HCS ready
2026/07/02 09:58:47.981916 [HCN] Initialized HCN API from computenetwork.dll
2026/07/02 09:58:47.997337 [HCN] EnumerateNetworks result: []
2026/07/02 09:58:48.248134 [Server] Signature verification initialized
2026/07/02 09:58:48.248134 [Server] Service: C:\Program Files\WindowsApps\Claude_1.17377.2.0_x64__pzs8sxrjxfjjc\app\resources\cowork-svc.exe
2026/07/02 09:58:48.248134 [Server] Subject: Anthropic, PBC
2026/07/02 09:58:48.248134 [Server] Thumbprint: dbde5d16768ed0c1...
2026/07/02 09:58:48.248134 [Server] Enforce: true
2026/07/02 09:58:48.248134 [Server] Starting named pipe server on \\.\pipe\cowork-vm-service
2026/07/02 09:58:48.248642 [Server] Named pipe server listening
2026/07/02 09:58:48.248642 Service ready. Listening on \\.\pipe\cowork-vm-service
2026/07/02 09:58:58.939060 [Server] Client connected
2026/07/02 09:59:00.050958 [Server] Client signature verified: D:\WindowsApps\Claude_1.17377.2.0_x64__pzs8sxrjxfjjc\app\claude.exe (subject: Anthropic, PBC)
2026/07/02 09:59:00.052033 [Server] Client connected: user=derkd exe=claude.exe isDev=false
2026/07/02 09:59:00.052597 [VM] VM owner set: id=cowork-vm-9d09517d sid=S-1-5-21-3673970679-1154737977-1649588588-1001
2026/07/02 09:59:00.052597 [VM] Event callbacks set
2026/07/02 09:59:00.052597 [Server] Created new VM session for derkd:C:\Users\derkd\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude
2026/07/02 09:59:00.053230 [Server] Persistent RPC: entering loop
2026/07/02 09:59:08.248938 [IdleCheck] Session derkd:C:\Users\derkd\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude: starting idle timer now
2026/07/08 16:21:03.831533 [Server] Persistent RPC: connection ended: failed to read length: EOF
2026/07/08 16:21:03.893662 [Server] Session derkd:C:\Users\derkd\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude has no active connections, idle timeout starts
2026/07/08 16:21:04.444124 Service stop requested
2026/07/08 16:21:04.445241 Shutdown signal received...
2026/07/08 16:21:04.445241 [Server] Stopping server...
2026/07/08 16:21:04.481283 [Server] Stopping VM for session derkd:C:\Users\derkd\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude...
2026/07/08 16:21:04.482407 [VM] VM already stopped, nothing to release
2026/07/08 16:21:04.482407 [Server] Server stopped
2026/07/08 16:21:04.482407 Service stopped.
2026/07/08 16:21:19.272744 Starting CoworkVMService as Windows service
2026/07/08 16:21:19.428543 Claude VM Service starting...
2026/07/08 16:21:19.428543 Waiting for configuration from app via 'configure' method...
2026/07/08 16:21:19.428543 [HCS] Initializing HCS DLLs...
2026/07/08 16:21:19.430050 Warning: failed to open service for recovery config: Access is denied.
2026/07/08 16:21:19.453463 [HCS] vmcompute.dll loaded successfully
2026/07/08 16:21:19.468459 [HCS] computecore.dll loaded successfully
2026/07/08 16:21:19.469383 [HCS] Procs initialized, HCS ready
2026/07/08 16:21:19.469383 [HCN] Initialized HCN API from computenetwork.dll
2026/07/08 16:21:19.554388 [HCN] EnumerateNetworks result: []
2026/07/08 16:21:21.638668 [Server] Signature verification initialized
2026/07/08 16:21:21.638668 [Server] Service: C:\Program Files\WindowsApps\Claude_1.19367.0.0_x64__pzs8sxrjxfjjc\app\resources\cowork-svc.exe
2026/07/08 16:21:21.638668 [Server] Subject: Anthropic, PBC
2026/07/08 16:21:21.638668 [Server] Thumbprint: dbde5d16768ed0c1...
2026/07/08 16:21:21.638668 [Server] Enforce: true
2026/07/08 16:21:21.638668 [Server] Starting named pipe server on \\.\pipe\cowork-vm-service
2026/07/08 16:21:21.639852 [Server] Named pipe server listening
2026/07/08 16:21:21.639852 Service ready. Listening on \\.\pipe\cowork-vm-service
2026/07/08 16:21:43.936946 [Server] Client connected
2026/07/08 16:21:45.699570 [Server] Client signature verified: D:\WindowsApps\Claude_1.19367.0.0_x64__pzs8sxrjxfjjc\app\claude.exe (subject: Anthropic, PBC)
2026/07/08 16:21:45.700693 [Server] Client connected: user=derkd exe=claude.exe isDev=false
2026/07/08 16:21:45.701989 [VM] VM owner set: id=cowork-vm-9d09517d sid=S-1-5-21-3673970679-1154737977-1649588588-1001
2026/07/08 16:21:45.702429 [VM] Event callbacks set
2026/07/08 16:21:45.702429 [Server] Created new VM session for derkd:C:\Users\derkd\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude
2026/07/08 16:21:45.702429 [Server] Persistent RPC: entering loop
2026/07/08 16:21:51.641037 [IdleCheck] Session derkd:C:\Users\derkd\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude: starting idle timer now
2026/07/08 16:24:12.121629 [Server] Persistent RPC: connection ended: failed to read length: EOF
2026/07/08 16:24:12.159222 [Server] Session derkd:C:\Users\derkd\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude has no active connections, idle timeout starts
2026/07/08 16:24:23.772288 [Server] Client connected
2026/07/08 16:24:31.220161 [Server] Client signature verified: D:\WindowsApps\Claude_1.19367.0.0_x64__pzs8sxrjxfjjc\app\claude.exe (subject: Anthropic, PBC)
2026/07/08 16:24:31.245267 [Server] Client connected: user=derkd exe=claude.exe isDev=false
2026/07/08 16:24:31.275852 [Server] Persistent RPC: entering loop
2026/07/09 10:34:39.752506 [Server] Persistent RPC: connection ended: failed to read length: EOF
2026/07/09 10:34:39.788194 [Server] Session derkd:C:\Users\derkd\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude has no active connections, idle timeout starts
2026/07/09 10:34:57.190307 Service stop requested
2026/07/09 10:34:57.192019 Shutdown signal received...
2026/07/09 10:34:57.192019 [Server] Stopping server...
2026/07/09 10:34:57.232313 [Server] Stopping VM for session derkd:C:\Users\derkd\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude...
2026/07/09 10:34:57.240514 [VM] VM already stopped, nothing to release
2026/07/09 10:34:57.247745 [Server] Server stopped
2026/07/09 10:34:57.250259 Service stopped.
2026/07/09 10:36:09.945776 Starting CoworkVMService as Windows service
2026/07/09 10:36:10.274975 Claude VM Service starting...
2026/07/09 10:36:10.274975 Waiting for configuration from app via 'configure' method...
2026/07/09 10:36:10.276465 [HCS] Initializing HCS DLLs...
2026/07/09 10:36:10.275687 Warning: failed to open service for recovery config: Access is denied.
2026/07/09 10:36:10.631990 [HCS] vmcompute.dll loaded successfully
2026/07/09 10:36:10.935835 [HCS] computecore.dll loaded successfully
2026/07/09 10:36:10.936819 [HCS] Procs initialized, HCS ready
2026/07/09 10:36:10.941469 [HCN] Initialized HCN API from computenetwork.dll

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

1.20186.1 (df1d8a)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_

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