[BUG] Cowork "Virtualization is not available" on Windows 11 Pro desktop app — yukonSilver unsupported, VM never initializes

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 displays "Virtualization is not available — Claude's workspace requires Virtual Machine Platform, but the virtualization service isn't responding." Restarting does not resolve it. The %APPDATA%\Claude folder is never created, meaning the VM never attempts to initialize.

What Should Happen?

Cowork should be usable and virtualizations should respond in the desktop app

Error Messages/Logs

Virtualization is not available
Claude's workspace requires Virtual Machine Platform, but the virtualization service isn't responding. Restart your computer to resolve this.

Steps to Reproduce

What I've tried

Multiple clean reinstalls as Administrator
Full AppX and AppData cleanup via PowerShell
Upgraded from Windows 10 Pro 22H2 to Windows 11 Pro 25H2 — issue persists on both
Verified all virtualization features enabled

Note
This appears to be the same yukonSilver platform misclassification reported in #27316, #27420, #29887, #32004. Reproduces on both Windows 10 and Windows 11 on this hardware profile.

Claude Model

Sonnet (default)

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

Claude Desktop - version unknown (Cowork bug)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

Title: Cowork "Virtualization is not available" on Windows 11 Pro — yukonSilver unsupported, VM never initializes
Environment

OS: Windows 11 Pro Version 25H2 (OS Build 26200.8037)
Device: Lenovo ThinkPad X1 Carbon 5th Gen
Claude Desktop: latest installer from claude.ai/download
Subscription: Pro
Hyper-V: Enabled
Virtual Machine Platform: Enabled
Windows Hypervisor Platform: Enabled

What's happening
Cowork displays "Virtualization is not available — Claude's workspace requires Virtual Machine Platform, but the virtualization service isn't responding." Restarting does not resolve it. The %APPDATA%\Claude folder is never created, meaning the VM never attempts to initialize.
What I've tried

Multiple clean reinstalls as Administrator
Full AppX and AppData cleanup via PowerShell
Upgraded from Windows 10 Pro 22H2 to Windows 11 Pro 25H2 — issue persists on both
Verified all virtualization features enabled

Note
This appears to be the same yukonSilver platform misclassification reported in #27316, #27420, #29887, #32004. Reproduces on both Windows 10 and Windows 11 on this hardware profile.