[BUG] Cowork "yukonSilver not supported" on Windows 10 Pro 22H2 with Hyper-V running

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?

Cowork tab shows "requires a newer installation" banner.
yukonSilver is flagged as unsupported and VM never starts.

Environment:

• OS: Windows 10 Pro, Version 22H2, Build 19045.6456
• Processor: Intel Core i5-7300U
• RAM: 8GB
• Claude Desktop: latest (fresh install 3/15/2026)
• Hyper-V: Running (Get-Service vmms confirms)

Log output (cowork_vm_node.log):
[cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
[startVM] VM not supported (win32/x64), skipping

What Should Happen?

Cowork loads and runs — Hyper-V is active and OS meets stated requirements.

Error Messages/Logs

Cowork loads and runs — Hyper-V is active and OS meets stated requirements.

Steps to Reproduce

1. Fresh install of Claude Desktop v1.1.6679 on Windows 10 Pro 22H2 (Build 19045.6456)
2. Hyper-V enabled and running (Get-Service vmms returns Status: Running)
3. BIOS virtualization enabled (Task Manager > Performance > CPU shows Virtualization: Enabled)
4. Open Claude Desktop
5. Click Cowork tab
6. Banner shows "Cowork requires a newer installation"
7. cowork_vm_node.log shows yukonSilver marked unsupported on every launch — VM never starts

Additional context: Cowork briefly worked on this machine prior to a system reset. After reinstalling Claude Desktop v1.1.6679, the yukonSilver error appears on every launch with no workaround available.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

N/A

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_