[BUG] Claude Cowork shows "Virtual Machine Platform not available" — yukonSilver marked as unsupported despite all virtualization features enabled

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?

When I try to do my very first project on Claude Cowork its not working. Its written Virtualisierung ist nicht verfügbar
Claudes Workspace benötigt Virtual Machine Platform, aber der Virtualisierungsdienst antwortet nicht. Starte deinen Computer neu, um dies zu beheben.

What Should Happen?

Claude should help out with this problem so people me included could use Cowork without any problems

Error Messages/Logs

Virtualisierung ist nicht verfügbar
Claudes Workspace benötigt Virtual Machine Platform, aber der Virtualisierungsdienst antwortet nicht. Starte deinen Computer neu, um dies zu beheben.

Steps to Reproduce

1. Install Claude Desktop (latest version) from claude.ai/download on Windows 10 Pro
2. Open Windows Features ("Windows-Features aktivieren oder deaktivieren") and enable:

• Hyper-V
• Virtual Machine Platform
• Windows Hypervisor Platform

1. Run in PowerShell (as Administrator): bcdedit /set hypervisorlaunchtype auto
2. Restart the computer
3. Open Claude Desktop and navigate to the Cowork tab
4. Observe the error: "Virtualization is not available — Claude's workspace requires

Virtual Machine Platform, but the virtualization service isn't responding."

System verification:

• Get-Service CoworkVMService → Status: Running
• All three Windows virtualization features: Enabled
• cowork_vm_node.log shows repeatedly:

"yukonSilver not supported (status=unsupported), checking for stale bundle..."

• Restarting multiple times does not resolve the issue.

OS: Windows 10 Pro

Claude Model

Sonnet (default)

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

Claude Desktop v1.1062.0 (b81bcd) — Claude Code CLI not installed.

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Im looking forward to use Cowork ASAP. So I am thankful for reaching out.