[BUG] Cowork fails to start on Windows 11 Home - HRESULT 0x80070005 after app update

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 workspace fails to start with error: "failed to add Plan9 share 'd': HcsWaitForOperationResult failed with HRESULT 0x80070005: {"Error":-2147024891,"ErrorMessage":""}"

This worked before a recent Claude app update. After the update, Cowork has been broken for over a week with no fix.

Troubleshooting already attempted:

• Reinstalled Claude multiple times
• Restarted computer multiple times
• Manually created vm_bundles folder and granted SYSTEM:F permissions
• Manually enabled Hyper-V on Windows 11 Home via DISM
• Created Hyper-V Administrators group and added user
• Clicked "reinstall workspace" link inside Cowork — no effect
• Granted SYSTEM:F permissions to entire Claude AppData folder

None of the above resolved the issue.

OS: Windows 11 Home Single Language
Hyper-V: Enabled (manually via DISM, confirmed State: Enabled)
Error persists after all workarounds.

What Should Happen?

Cowork workspace should start successfully and allow running tasks.

Error Messages/Logs

failed to add Plan9 share 'd': HcsWaitForOperationResult failed with HRESULT 0x80070005: {"Error":-2147024891,"ErrorMessage":""}

Steps to Reproduce

1. Open Claude Desktop on Windows 11 Home
2. Click on Cowork tab
3. Error appears immediately on every attempt

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Unknown - stopped working after automatic update

Claude Code Version

Claude Desktop (not Claude Code CLI)

Platform

Other

Operating System

Windows

Terminal/Shell

Other

Additional Information

This is Claude Desktop's Cowork feature, not Claude Code CLI.
OS: Windows 11 Home Single Language
Hyper-V: Manually enabled via DISM (confirmed State: Enabled)
Workarounds attempted: reinstall Claude, reboot, create vm_bundles folder, grant SYSTEM:F permissions, create Hyper-V Administrators group, click "reinstall workspace" inside app. None worked.
Broken for 1+ week with no response from support.