[BUG] 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?

What's Wrong?
The Cowork tab displays "Virtual Machine Platform not available" and prompts me to enable the feature and restart, despite Virtual Machine Platform, Windows Hypervisor Platform, and Hyper-V all being enabled. Clicking "Restart now" in the dialog and rebooting does not resolve the issue. The root cause is that the VM configuration yukonSilver is being classified as unsupported, preventing the VM bundle from downloading and Cowork from initializing.
This is the same issue reported in #25136, #27316, #27420, and #29887.
Environment

Claude Desktop: v1.1.5368 (d12d02), installed from claude.ai/download with administrator privileges
OS: Windows 11 Pro Version 25H2 (OS Build 26200.7462)
Subscription: Pro
Hyper-V: Enabled
Virtual Machine Platform: Enabled
Windows Hypervisor Platform: Enabled
CoworkVMService: Running
systeminfo Hyper-V Requirements: "A hypervisor has been detected. Features required for Hyper-V will not be displayed."

What Should Happen?

Expected Behavior
Cowork should detect that all virtualization features are enabled and successfully start the VM workspace.
Actual Behavior
Cowork displays the "Virtual Machine Platform not available" error. The VM never initializes. The %APPDATA%\Claude\logs\cowork_vm_node.log shows repeated entries:
yukonSilver not supported (status=unsupported), checking for stale bundle...
Every log entry since installation (March 4–7, 2026) shows this same message. The VM never attempts to start.
Additional Notes

Cowork works correctly on a separate Windows PC at my office with the same Pro subscription
The home PC was freshly reinstalled with Claude Desktop using administrator privileges after encountering this issue
All three Windows virtualization features were verified enabled via the Windows Features dialog
CoworkVMService confirmed running via Get-Service CoworkVMService
Hardware virtualization confirmed active via systeminfo

Error Messages/Logs

2026-03-04 19:37:14 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-03-04 20:35:36 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-03-06 19:20:47 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-03-06 21:28:44 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-03-07 19:46:31 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-03-07 19:49:08 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-03-07 19:53:07 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-03-07 19:53:39 [info] [logout] User navigated to /logout, stopping VM
2026-03-07 19:53:39 [info] [VM] Loading vmClient (TypeScript) module...
2026-03-07 19:53:39 [info] [VM] Module loaded successfully
2026-03-07 19:53:39 [info] [stopVM] stopping VM gracefully
2026-03-07 19:53:40 [error] [logout] Failed to stop VM on logout: not configured: call 'configure' first
2026-03-07 20:06:23 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-03-07 20:16:21 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-03-07 20:22:27 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...

Steps to Reproduce

Steps to Reproduce

Install Claude Desktop v1.1.5368 from claude.ai/download as administrator
Enable Hyper-V, Virtual Machine Platform, and Windows Hypervisor Platform in Windows Features
Restart computer
Launch Claude Desktop and navigate to the Cowork tab
Observe "Virtual Machine Platform not available" error

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

1.1.5368 (d12d02)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_