[BUG] Cowork fails with HCS 0x800707de after virtiofs/Plan9 mount error - Windows 11

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 fails to start on Windows 11. The error progresses in two stages:

What Should Happen?

The VM service starts (CoworkVMService shows Running) but the Cowork workspace never initializes. Restarting Claude Desktop does not fix it. Reinstalling the app does not fix it.

Error Messages/Logs

RPC error -1: failed to ensure virtiofs mount: Plan9 mount failed: bad address

HCS operation failed: failed to create compute system: HcsWaitForOperationResult failed with HRESULT 0x800707de: {"Error":-2147022882,"ErrorMessage":"","Attribution":[{"OperationFailure":{"Detail":"Construct"}}]}

The VM service starts (CoworkVMService shows Running) but the Cowork workspace never initializes. Restarting Claude Desktop does not fix it. Reinstalling the app does not fix it.

Steps to Reproduce

Open Claude Desktop (Store version 1.1.5368)
Click on Cowork tab
Error appears immediately: RPC error -1: failed to ensure virtiofs mount: Plan9 mount failed: bad address
After bundle reset (vm_bundles\claudevm.bundle deleted and recreated), error changes to HCS operation failed: HRESULT 0x800707de
CoworkVMService shows Running in Services but workspace never loads

Claude Model

Opus

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

Claude Desktop Version1.1.5368

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Troubleshooting Already Attempted

Restarted Claude Desktop multiple times
Restarted the computer
Reinstalled Claude Desktop
Stopped CoworkVMService, deleted claude-code-vm and vm_bundles folders, restarted service
Deleted claudevm.bundle to force full re-download
Verified HypervisorPlatform and VirtualMachinePlatform are both Enabled
Verified vmcompute and hns services are Running
Confirmed no conflicting virtualization software (no WSL2, Docker, VMware)

Expected Behavior
Cowork workspace should initialize successfully and accept task input.

Relevant Logs
cowork_vm_node.log (repeating loop):
[warn] [Keepalive] Ping failed: VM service not running. The service failed to start.
main.log:
[error] Sentry caught: {
type: 'Error',
value: 'VM service not running. The service failed to start.'
}