[BUG] Cowork shows "Virtualization is not available" on Windows 11 Pro with AMD CPU — VM never initializes, no logs created

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?

[BUG] Cowork shows "Virtualization is not available" on Windows 11 Pro with AMD CPU — VM never initializes, no logs created

Preflight Checklist

• [x] I have searched existing issues and this is related to but not resolved by: #27316, #27420, #32004, #38632
• [x] I am using the latest version of Claude Desktop

Environment

• OS: Microsoft Windows 11 Pro, Version 10.0.26200
• CPU: AMD (SVM Mode: Enabled in BIOS)
• Claude Desktop version: latest (installed fresh from claude.ai/download as Administrator)
• Subscription: Pro

Virtualization Status (all confirmed enabled)

• BIOS/UEFI: AMD SVM Mode → Enabled
• VirtualizationFirmwareEnabled (WMI): True
• VirtualMachinePlatform: Enabled
• Microsoft-Hyper-V: Enabled
• HypervisorPlatform: Enabled
• CoworkVMService: Running
• vmcompute service: Running
• hcsdiag list: empty (no VMs registered)

What's Wrong?

Cowork displays "Virtualization is not available — The Claude workspace requires Virtual Machine Platform, but the virtualization service is not responding" despite all virtualization prerequisites being fully enabled at both BIOS and Windows level.

The VM never attempts to initialize. The %APPDATA%\Claude\logs folder does not exist at all, suggesting Cowork fails silently before creating any logs.

Steps to Reproduce

1. Install Claude Desktop from claude.ai/download as Administrator on Windows 11 Pro with AMD CPU
2. Verify all virtualization features enabled (VirtualMachinePlatform, Microsoft-Hyper-V, HypervisorPlatform)
3. Verify CoworkVMService and vmcompute are Running
4. Verify AMD SVM Mode enabled in BIOS
5. Navigate to Cowork tab in Claude Desktop
6. Observe "Virtualization is not available" error
7. Check %APPDATA%\Claude\logs — folder does not exist
8. Run hcsdiag list — returns empty

Attempted Fixes (error persists after all)

• Enabled all Windows optional features via PowerShell (Admin)
• Restarted CoworkVMService and vmcompute manually
• Deleted %APPDATA%\Claude\vm_bundles (did not exist)
• Full uninstall, AppData cleanup, reinstall as Administrator
• Upgraded from Windows 10 Pro to Windows 11 Pro
• Verified and confirmed AMD SVM Mode enabled in BIOS

Expected Behavior

Cowork should detect that all virtualization features are enabled and successfully start the VM workspace.

Actual Behavior

Cowork displays the "Virtualization is not available" error. The VM never initializes. No logs are created under %APPDATA%\Claude\. hcsdiag list returns empty, confirming no VM is ever registered with the Host Compute Service.

Additional Context

This appears to be the same underlying issue as #27316, #27420, #32004, and #38632, specifically affecting AMD CPUs. The issue persisted after upgrading from Windows 10 Pro to Windows 11 Pro, suggesting it is not an OS version issue but rather a problem with Cowork's interaction with AMD virtualization (SVM) or the Host Compute Service on AMD hardware.

What Should Happen?

Cowork should detect that all virtualization features are enabled and successfully start the VM workspace.

Error Messages/Logs

Steps to Reproduce

Install Claude Desktop from claude.ai/download as Administrator on Windows 11 Pro with AMD CPU
Verify all virtualization features enabled (VirtualMachinePlatform, Microsoft-Hyper-V, HypervisorPlatform)
Verify CoworkVMService and vmcompute are Running
Verify AMD SVM Mode enabled in BIOS
Navigate to Cowork tab in Claude Desktop
Observe "Virtualization is not available" error
Check %APPDATA%\Claude\logs — folder does not exist
Run hcsdiag list — returns empty

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude Anthropic.Claude 1.569.0.0

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_