[BUG] Cowork VM service not running - yukonSilver unsupported, VM bundle deleted in loop

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?

System info:

Windows 11 25H2
Intel i7-14700HX
Claude Desktop v1.1.7714.0

What's happening:

CoworkVMService installs but immediately stops and won't start
Log shows yukonSilver not supported (status=unsupported)
VM bundle files are being deleted in a loop before the VM can start
One instance of ERR_QUIC_PROTOCOL_ERROR during download

What you've tried:

Restarted Claude Desktop and computer
Cleared cache and reinstalled workspace
Deleted vm_bundles folder manually
Enabled HypervisorPlatform via PowerShell
Ran Claude Desktop as administrator
Ran netsh int tcp set global autotuninglevel=normal

To file the report:
Go to github.com/anthropics/claude-code/issues and click New Issue

What Should Happen?

Cowork should start successfully and the VM service should remain running, allowing me to use the workspace. The VM bundle files should not be deleted in a loop before the VM has a chance to start.

Error Messages/Logs

2026-03-23 10:37:40 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-03-23 10:37:41 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-03-23 10:39:22 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-03-23 10:43:30 [info] [Bundle:status] rootfs.vhdx missing
2026-03-23 10:43:30 [info] [VM] Loading vmClient (TypeScript) module...
2026-03-23 10:43:30 [info] [VM] Module loaded successfully
2026-03-23 10:43:30 [info] [Bundle:status] rootfs.vhdx missing
2026-03-23 10:43:31 [info] [Bundle:status] rootfs.vhdx missing
2026-03-23 10:43:31 [info] [warm] No warm file found for rootfs.vhdx at current version
2026-03-23 10:43:31 [info] [cache] No cached compressed file for rootfs.vhdx
2026-03-23 10:43:31 [info] rootfs.vhdx not found, downloading...
2026-03-23 10:43:31 [info] Downloading rootfs.vhdx...
2026-03-23 10:44:00 [info] [stopVM] stopping VM gracefully
2026-03-23 10:44:05 [info] [deleteVMBundle] Deleting reinstall files from C:\Users\ik08\AppData\Roaming\Claude\vm_bundles\claudevm.bundle
2026-03-23 10:44:05 [info] [deleteVMBundle] Reinstall files deleted (sessiondata.img and rootfs.img.zst preserved)
2026-03-23 10:44:06 [info] [VM] Loading vmClient (TypeScript) module...
2026-03-23 10:44:06 [info] [VM] Module loaded successfully
2026-03-23 10:44:07 [info] [Bundle:status] rootfs.vhdx missing
2026-03-23 10:44:07 [info] [Bundle:status] rootfs.vhdx missing
2026-03-23 10:44:07 [info] [Bundle:status] rootfs.vhdx missing
2026-03-23 10:44:07 [info] [warm] No warm file found for rootfs.vhdx at current version
2026-03-23 10:44:07 [info] [cache] No cached compressed file for rootfs.vhdx
2026-03-23 10:44:07 [info] rootfs.vhdx not found, downloading...
2026-03-23 10:44:07 [info] Downloading rootfs.vhdx...
2026-03-23 10:49:36 [info] [VM] Loading vmClient (TypeScript) module...
2026-03-23 10:49:36 [info] [VM] Module loaded successfully
2026-03-23 10:49:36 [info] [Bundle:status] rootfs.vhdx missing
2026-03-23 10:49:36 [info] [Bundle:status] rootfs.vhdx missing
2026-03-23 10:49:36 [info] [Bundle:status] rootfs.vhdx missing
2026-03-23 10:49:36 [info] [warm] No warm file found for rootfs.vhdx at current version
2026-03-23 10:49:36 [info] [cache] No cached compressed file for rootfs.vhdx
2026-03-23 10:49:36 [info] rootfs.vhdx not found, downloading...
2026-03-23 10:49:36 [info] Downloading rootfs.vhdx...
2026-03-23 10:50:14 [info] rootfs.vhdx.zst checksum validated
2026-03-23 10:50:14 [info] [downloadVM] Saved compressed rootfs.vhdx to cache
2026-03-23 10:50:14 [info] [Bundle:status] vmlinuz missing
2026-03-23 10:50:14 [info] [warm] No warm file found for vmlinuz at current version
2026-03-23 10:50:14 [info] [cache] No cached compressed file for vmlinuz
2026-03-23 10:50:14 [info] vmlinuz not found, downloading...
2026-03-23 10:50:14 [info] Downloading vmlinuz...
2026-03-23 10:50:14 [info] vmlinuz.zst checksum validated
2026-03-23 10:50:14 [info] [downloadVM] Saved compressed vmlinuz to cache
2026-03-23 10:50:14 [info] [Bundle:status] initrd missing
2026-03-23 10:50:14 [info] [warm] No warm file found for initrd at current version
2026-03-23 10:50:14 [info] [cache] No cached compressed file for initrd
2026-03-23 10:50:14 [info] initrd not found, downloading...
2026-03-23 10:50:14 [info] Downloading initrd...
2026-03-23 10:50:17 [info] initrd.zst checksum validated
2026-03-23 10:50:17 [info] [downloadVM] Saved compressed initrd to cache
2026-03-23 10:50:17 [info] All files ready in C:\Users\ik08\AppData\Roaming\Claude\vm_bundles\claudevm.bundle
2026-03-23 10:53:17 [info] [stopVM] stopping VM gracefully
2026-03-23 10:53:23 [info] [Bundle:status] rootfs.vhdx missing
2026-03-23 10:53:23 [info] [VM] Loading vmClient (TypeScript) module...
2026-03-23 10:53:23 [info] [VM] Module loaded successfully
2026-03-23 10:53:23 [info] [Bundle:status] rootfs.vhdx missing
2026-03-23 10:53:23 [info] [Bundle:status] rootfs.vhdx missing
2026-03-23 10:53:23 [info] [warm] No warm file found for rootfs.vhdx at current version
2026-03-23 10:53:23 [info] [cache] No cached compressed file for rootfs.vhdx
2026-03-23 10:53:23 [info] rootfs.vhdx not found, downloading...
2026-03-23 10:53:23 [info] Downloading rootfs.vhdx...
2026-03-23 10:53:47 [error] [download] VM download failed: Request error: net::ERR_QUIC_PROTOCOL_ERROR
2026-03-23 11:02:31 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-03-23 11:02:31 [info] [deleteVMBundle] Deleting reinstall files from C:\Users\ik08\AppData\Roaming\Claude\vm_bundles\claudevm.bundle
2026-03-23 11:02:31 [info] [deleteVMBundle] Reinstall files deleted (sessiondata.img and rootfs.img.zst preserved)
2026-03-23 11:03:16 [info] [Bundle:status] rootfs.vhdx missing
2026-03-23 11:03:16 [info] [VM] Loading vmClient (TypeScript) module...
2026-03-23 11:03:16 [info] [VM] Module loaded successfully
2026-03-23 11:03:16 [info] [Bundle:status] rootfs.vhdx missing
2026-03-23 11:03:16 [info] [Bundle:status] rootfs.vhdx missing
2026-03-23 11:03:16 [info] [warm] No warm file found for rootfs.vhdx at current version
2026-03-23 11:03:16 [info] [cache] No cached compressed file for rootfs.vhdx
2026-03-23 11:03:16 [info] rootfs.vhdx not found, downloading...
2026-03-23 11:03:16 [info] Downloading rootfs.vhdx...
2026-03-23 11:04:04 [info] rootfs.vhdx.zst checksum validated
2026-03-23 11:04:04 [info] [downloadVM] Saved compressed rootfs.vhdx to cache
2026-03-23 11:04:04 [info] [Bundle:status] vmlinuz missing
2026-03-23 11:04:04 [info] [warm] No warm file found for vmlinuz at current version
2026-03-23 11:04:04 [info] [cache] No cached compressed file for vmlinuz
2026-03-23 11:04:04 [info] vmlinuz not found, downloading...
2026-03-23 11:04:04 [info] Downloading vmlinuz...
2026-03-23 11:04:04 [info] vmlinuz.zst checksum validated
2026-03-23 11:04:04 [info] [downloadVM] Saved compressed vmlinuz to cache
2026-03-23 11:04:04 [info] [Bundle:status] initrd missing
2026-03-23 11:04:04 [info] [warm] No warm file found for initrd at current version
2026-03-23 11:04:04 [info] [cache] No cached compressed file for initrd
2026-03-23 11:04:04 [info] initrd not found, downloading...
2026-03-23 11:04:04 [info] Downloading initrd...
2026-03-23 11:04:07 [info] initrd.zst checksum validated
2026-03-23 11:04:07 [info] [downloadVM] Saved compressed initrd to cache
2026-03-23 11:04:07 [info] All files ready in C:\Users\ik08\AppData\Roaming\Claude\vm_bundles\claudevm.bundle
2026-03-23 11:18:13 [info] [VM] Loading vmClient (TypeScript) module...
2026-03-23 11:18:13 [info] [VM] Module loaded successfully
2026-03-23 11:22:18 [info] [VM] Loading vmClient (TypeScript) module...
2026-03-23 11:22:18 [info] [VM] Module loaded successfully
2026-03-23 11:26:54 [info] [VM] Loading vmClient (TypeScript) module...
2026-03-23 11:26:54 [info] [VM] Module loaded successfully
2026-03-23 11:27:59 [info] [stopVM] stopping VM gracefully
2026-03-23 11:28:04 [info] [deleteVMBundle] Deleting reinstall files from C:\Users\ik08\AppData\Roaming\Claude\vm_bundles\claudevm.bundle
2026-03-23 11:28:04 [info] [deleteVMBundle] Reinstall files deleted (sessiondata.img and rootfs.img.zst preserved)
2026-03-23 11:28:05 [info] [VM] Loading vmClient (TypeScript) module...
2026-03-23 11:28:05 [info] [VM] Module loaded successfully
2026-03-23 11:42:02 [info] [VM] Loading vmClient (TypeScript) module...
2026-03-23 11:42:02 [info] [VM] Module loaded successfully
2026-03-23 11:48:07 [info] [stopVM] stopping VM gracefully
2026-03-23 11:48:12 [info] [deleteVMBundle] Deleting reinstall files from C:\Users\ik08\AppData\Roaming\Claude\vm_bundles\claudevm.bundle
2026-03-23 11:48:12 [info] [deleteVMBundle] Reinstall files deleted (sessiondata.img and rootfs.img.zst preserved)
2026-03-23 11:48:13 [info] [VM] Loading vmClient (TypeScript) module...
2026-03-23 11:48:13 [info] [VM] Module loaded successfully
2026-03-23 11:49:08 [info] [VM] Loading vmClient (TypeScript) module...
2026-03-23 11:49:08 [info] [VM] Module loaded successfully
2026-03-23 15:15:30 [info] [VM] Loading vmClient (TypeScript) module...
2026-03-23 15:15:30 [info] [VM] Module loaded successfully
2026-03-23 15:18:13 [info] [stopVM] stopping VM gracefully
2026-03-23 15:18:18 [info] [deleteVMBundle] Deleting reinstall files from C:\Users\ik08\AppData\Roaming\Claude\vm_bundles\claudevm.bundle
2026-03-23 15:18:18 [info] [deleteVMBundle] Reinstall files deleted (sessiondata.img and rootfs.img.zst preserved)
2026-03-23 15:18:19 [info] [VM] Loading vmClient (TypeScript) module...
2026-03-23 15:18:19 [info] [VM] Module loaded successfully
2026-03-23 15:24:16 [info] [VM] Loading vmClient (TypeScript) module...
2026-03-23 15:24:16 [info] [VM] Module loaded successfully
2026-03-23 15:24:26 [info] [stopVM] stopping VM gracefully
2026-03-23 15:24:31 [info] [deleteVMBundle] Deleting reinstall files from C:\Users\ik08\AppData\Roaming\Claude\vm_bundles\claudevm.bundle
2026-03-23 15:24:31 [info] [deleteVMBundle] Reinstall files deleted (sessiondata.img and rootfs.img.zst preserved)
2026-03-23 15:24:33 [info] [VM] Loading vmClient (TypeScript) module...
2026-03-23 15:24:33 [info] [VM] Module loaded successfully

Steps to Reproduce

Install Claude Desktop on Windows 11 25H2
Open Claude Desktop and navigate to Cowork
Observe error: "Failed to start Claude's workspace — VM service not running. The service failed to start."
Check logs at %APPDATA%\Claude\logs\cowork_vm_node.log — shows yukonSilver not supported and VM bundle being deleted in a loop
Error persists after restarting Claude, rebooting, clearing cache, reinstalling workspace, and enabling HypervisorPlatform

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

N/A

Claude Code Version

1.1.7714.0

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

Hyper-V features status:

VirtualMachinePlatform: Enabled
HypervisorPlatform: Enabled (had to manually enable this via PowerShell)
HyperVisorPresent: True

Troubleshooting already attempted:

Ran netsh int tcp set global autotuninglevel=normal to address ERR_QUIC_PROTOCOL_ERROR
Manually enabled HypervisorPlatform via Enable-WindowsOptionalFeature
CoworkVMService confirmed installed but stops immediately when started manually via PowerShell
No third-party antivirus running

Key log errors to highlight:

yukonSilver not supported (status=unsupported)
ERR_QUIC_PROTOCOL_ERROR during VM file download
VM bundle files being repeatedly deleted before VM can start

The fact that you had to manually enable HypervisorPlatform is worth calling out specifically — it's possible the Claude installer isn't enabling it automatically on some systems, which could be affecting other users too.