[BUG]

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 VM fails to start on Windows 11 Pro x64 with HYPERVISOR_SERVICE_ERROR / HRESULT 0x80370102 despite Hyper-V being fully enabled and the hypervisor confirmed running via systeminfo. Additionally, the preflight check incorrectly marks yukonSilver as unsupported on a fully capable system. Network diagnostics attempt to run macOS commands (/sbin/ifconfig, /usr/sbin/scutil, /usr/sbin/kextstat) on Windows, all failing with ENOENT.

What Should Happen?

Cowork should detect the active hypervisor, pass the yukonSilver support check, boot the VM successfully, and use Windows-appropriate diagnostic commands (e.g., ipconfig, Get-NetAdapter)

Error Messages/Logs

[error] [VM:start] VM boot failed: HCS operation failed: failed to create compute system: HcsWaitForOperationResult failed with HRESULT 0x80370102: {"Error":-2143878910,"ErrorMessage":"The virtual machine could not be started because a required feature is not installed.","ErrorEvents":[{"Message":"Cannot create system 'cowork-vm' since Hyper-V is not installed on the host."}]}

[error] [VM:start] HCS error detected, firmwareVirt=true, sentinel=HYPERVISOR_SERVICE_ERROR

[info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...

[warn] [startVM] VM not supported (win32/x64), skipping

[error] [networkDiagnostics] Failed to run /sbin/ifconfig: spawn /sbin/ifconfig ENOENT

Steps to Reproduce

Windows 11 Pro x64, Intel CPU with VT-x and VT-d enabled in BIOS
Enable Hyper-V, Virtual Machine Platform, and Windows Hypervisor Platform in Windows Features
Confirm bcdedit /set hypervisorlaunchtype auto
Confirm hypervisor running: systeminfo shows "A hypervisor has been detected"
Install Claude desktop app (Microsoft Store), open Cowork tab
Observe: yukonSilver not supported in preflight, then HRESULT 0x80370102 on every VM boot attempt
App enters infinite retry loop (30+ attempts in logs within minutes)

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude Desktop 1.1.3918

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

Three distinct bugs in one log: (1) false yukonSilver unsupported detection, (2) HCS 0x80370102 despite active hypervisor, (3) macOS diagnostic paths on Windows
firmwareVirt=true in the newer app version confirms the app detects virtualization at firmware level but still fails at HCS layer
Related issues: #25136, #27010, #25155
Full cowork_vm_node.log available — covers Feb 5 through Feb 21 with hundreds of failed attempts
Attaching the complete log file is recommended