[BUG] Cowork "yukonSilver not supported" on Windows 11 Business — persists after full clean reinstall

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 shows a "Reinstall the desktop app to access Cowork" banner. Clicking the Reinstall button does nothing. After manually downloading and reinstalling from claude.ai/download, the banner persists. The log confirms the VM never attempts to start.

What Should Happen?

Cowork should detect Windows 11 Business as a supported platform and start the VM workspace.

Error Messages/Logs

From %APPDATA%\Claude\logs\cowork_vm_node.log:

2026-04-30 18:24:08 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...

This is the entire log — the VM never progresses past this check.

Steps to Reproduce

1. Download and install Claude Desktop MSIX from claude.ai/download as Administrator
2. Open Claude Desktop and click the Cowork tab
3. Observe "Reinstall the desktop app to access Cowork" banner

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude Code not installed

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

Regular Claude chat works perfectly. The issue is isolated to Cowork. This appears to be the same faulty platform detection reported in #25136, #32004, #47327 and others.

Troubleshooting Already Attempted

• Full uninstall + deletion of %APPDATA%\Claude and %LOCALAPPDATA%\Claude
• Fresh reinstall from claude.ai/download, run as Administrator
• Ran Get-AppxPackage -Name "Claude" | Remove-AppxPackage in PowerShell as Administrator before reinstalling
• Confirmed Virtual Machine Platform: Enabled
• Confirmed Hyper-V: Enabled