[BUG] Cowork "Virtualization is not available" on Windows 11 Pro 25H2 despite Hyper-V fully 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?

Cowork tab shows "Virtualization is not available — Claude's workspace
requires Virtual Machine Platform, but the virtualization service isn't
responding." Restarting does not resolve the issue.

System Info

• OS: Windows 11 Pro Version 25H2 (OS Build 26200.7922)
• GPU: NVIDIA RTX 4090

Verification Steps Completed

| Check | Result |
|---|---|
| Microsoft-Hyper-V | ✅ Enabled |
| hypervisorlaunchtype | ✅ Auto |
| VM Monitor Mode Extensions | ✅ Yes |
| VirtualMachinePlatform | ✅ Enabled |

Actual Behavior

Cowork shows "Virtualization is not available" error.
VM bundle downloads, then fails with HYPERVISOR_SERVICE_ERROR.

Log Output (cowork_vm_node.log)

What Should Happen?

Cowork should detect that all virtualization features are enabled and successfully initialize the workspace VM without errors.

Error Messages/Logs

[error] [VM:start] VM boot failed: HcsWaitForOperationResult failed with HRESULT 0x80370102
[error] [VM:start] Startup failed: Error: HYPERVISOR_SERVICE_ERROR
[warn] [VM:start] Heartbeat restart failed, leaving VM offline

Steps to Reproduce

Steps to Reproduce

1. Open Claude Desktop on Windows 11 Pro 25H2
2. Click Cowork tab
3. Error appears immediately

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

N/A - Claude Desktop app

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_