[BUG] Cowork on Windows 11 reports virtualization not enabled when it actually is

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?

On Windows 11, the Cowork desktop app reports "virtualization is not enabled" even though virtualization is confirmed enabled in Task Manager (Performance → CPU).

System details:

• OS: Windows 11 (latest updates applied)
• CPU: Intel Core i9-9900KF @ 3.60GHz
• Virtualization: Enabled (confirmed in Task Manager)

The problem follows a frustrating cycle:

1. Cowork reports virtualization is not enabled and refuses to run.
2. If VirtualMachinePlatform is disabled via terminal, Cowork starts but shows "an additional step must be performed."
3. That step re-enables VirtualMachinePlatform — and the cycle repeats from step 1.

WSL has also been fully uninstalled to rule it out, but the issue persists.

Full troubleshooting session with Claude: https://claude.ai/share/f83171b3-5a4b-47b2-89f2-7ff887d993fe

What Should Happen?

Cowork should correctly detect that virtualization is enabled on Windows 11 and launch successfully without requiring the user to disable VirtualMachinePlatform.

Error Messages/Logs

Steps to Reproduce

1. Install Cowork on Windows 11 with virtualization enabled (confirmed in Task Manager → Performance → CPU).
2. Launch the Cowork desktop app.
3. Cowork reports "virtualization is not enabled" and refuses to start.

Workaround attempted (leads to a cycle):

1. Disable VirtualMachinePlatform via terminal: dism /online /disable-feature /featurename:VirtualMachinePlatform
2. Launch Cowork again — it starts but shows "an additional step must be performed."
3. Following that step re-enables VirtualMachinePlatform.
4. Return to step 2 — the error appears again.

Additional steps tried:

• Fully uninstalled WSL — issue persists.

Output of List from "_Get-WindowsOptionalFeature -Online | Where-Object {$_.State -eq "Enabled"} | Select-Object FeatureName_"
Printing-XPSServices-Features
WorkFolders-Client
NetFx3
WCF-Services45
WCF-TCP-PortSharing45
MediaPlayback
WindowsMediaPlayer
SmbDirect
NetFx4-AdvSrvs
Printing-PrintToPDFServices-Features
MSRDC-Infrastructure
Printing-Foundation-Features
Printing-Foundation-InternetPrinting-Client
SearchEngine-Client-Package
Microsoft-RemoteDesktopConnection
Microsoft-Hyper-V-All
Microsoft-Hyper-V
Microsoft-Hyper-V-Tools-All
Microsoft-Hyper-V-Management-PowerShell
Microsoft-Hyper-V-Hypervisor
Microsoft-Hyper-V-Services
Microsoft-Hyper-V-Management-Clients

Claude Model

Sonnet (default)

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

latest (Cowork desktop app)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

Using the Cowork desktop app on Windows 11 (not a terminal/shell). Selected "Other" above as there is no desktop app option in the Terminal/Shell list.