claude-code - 💡(How to fix) Fix [BUG] Cowork VM fails during process - yukonSilver unsupported, @ant/claude-swift module missing [1 comments, 2 participants]

Preflight Checklist

• I have searched existing issues and this hasn't been reported yet
• This is a single bug report (please file separate reports for different bugs)
• I am using the latest version of Claude Code

What's Wrong?

The Cowork VM starts correctly but crashes mid-process after a short time. The error message shown is: "Virtualization not available – Claude's Workspace requires Virtual Machine Platform, but the virtualization service is not responding."

Temporarily fixed by: Help → Troubleshooting → "Delete Cowork VM bundle and restart", but the error returns after a while. The VM also crashes mid-task, not just at startup — for example, it started transcribing a video file using Whisper, then crashed during the process. Cowork then fell back to an online search instead of using the actual video content.

What Should Happen?

The Cowork VM should start reliably and remain stable throughout the entire duration of a task without crashing mid-process.

Error Messages/Logs

From claude_vm_node.log (recurring across multiple app versions):

2026-01-16 09:42:58 [info]  [SwiftVM] Loading @ant/claude-swift module...
2026-01-16 09:42:58 [error] [SwiftVM] Failed to load module: Error: Cannot find 
package '@ant/claude-swift' 
(ERR_MODULE_NOT_FOUND)

2026-01-16 09:43:56 [info]  [cleanupVMBundleIfUnsupported] yukonSilver not 
supported (status=unsupported), checking for stale bundle...

2026-01-19 09:43:08 [info]  [Bundle:status] rootfs.img missing

This pattern repeats across app versions 1.0.3218, 1.1.280, and 1.1.381.
The @ant/claude-swift module is missing in every version.
yukonSilver is consistently flagged as unsupported.
rootfs.img is repeatedly reported as missing after the bundle reset.

Steps to Reproduce

1. Open Claude Desktop, navigate to Cowork tab
2. Provide a video file and ask Cowork to transcribe and summarize it
3. Cowork starts the VM and begins processing
4. After a short time, the VM crashes mid-process with the virtualization error
5. Workaround: Help → Troubleshooting → "Delete Cowork VM bundle and restart"
6. Error disappears temporarily but returns after a while

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

Unknown – issue has been present across versions 1.0.3218, 1.1.280, and 1.1.381 So says the Claude chat.

Claude Code Version

Claude Desktop 1.1.381 (latest)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Full Windows virtualization configuration has been verified and is correct:

• Virtual Machine Platform (Plattform für virtuelle Computer): enabled
• Windows Hypervisor Platform: enabled
• CoworkVMService: running, StartType = Automatic
• vmcompute service: running
• bcdedit hypervisorlaunchtype: Auto
• Reinstalled Claude Desktop as Administrator: no improvement
• bcdedit fix (set hypervisorlaunchtype auto) from issue #60262: already set, no effect

The log files strongly suggest the root cause is that yukonSilver VM technology is flagged as unsupported on this system, causing the @ant/claude-swift module to fail loading and rootfs.img to go missing repeatedly.

Log files (claude_vm_node.log and cowork_vm_node.log) are attached.

Related issue: #60262

claude_vm_node.log cowork_vm_node.log