[BUG] Windows 11 Pro 25H2 Build 26200.8117

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?

Claude Cowork tab never appears and the VM is never provisioned on Windows 11 Pro 25H2 Build 26200.8117 (stable GA release). Every time Claude Desktop launches, the cowork_vm_node.log shows:

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

The app shows a banner asking to reinstall, but reinstalling does not fix the issue. Hyper-V, Virtual Machine Platform, and Windows Hypervisor Platform are all enabled. A clean uninstall and fresh install from claude.ai/download was performed, with no prior Squirrel-based installation remaining.

What Should Happen?

The Cowork tab should load and the yukonSilver VM should be provisioned normally. Windows 11 Pro 25H2 Build 26200.8117 is the current stable GA release and should be recognized as a supported platform. The platform detection logic should not mark this build as unsupported.

Error Messages/Logs

PS C:\WINDOWS\system32> Get-Content "$env:APPDATA\Claude\logs\cowork_vm_node.log" -Tail 30
2026-04-13 10:14:16 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...

Steps to Reproduce

1. Install Windows 11 Pro 25H2 (Build 26200.8117) — current stable GA release
2. Enable Hyper-V, Virtual Machine Platform, and Windows Hypervisor Platform

via Windows Features (all confirmed enabled)

1. Enable Developer Mode in Settings → System → For Developers
2. Download the latest Claude Desktop installer from claude.ai/download
3. Run the installer without administrator privileges (double-click only)
4. Launch Claude Desktop
5. Navigate to the Cowork tab
6. Observe the banner "Cowork requires a newer installation"
7. Click "Reinstall" button — nothing happens
8. Check log at %APPDATA%\Claude\logs\cowork_vm_node.log and observe:

[cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported)
[startVM] VM not supported (win32/x64), skipping

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude 1.1617.0 (8d6345)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_