[BUG] CoworkVMService Running but App Reports "VM service not running"

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 displays "Failed to start Claude's workspace — VM service not running. The service failed to start." However, when querying via PowerShell, CoworkVMService is confirmed to be in STATE 4 (RUNNING) with no error codes.

The app and the service are failing to connect to each other despite the service running successfully.

Steps to Reproduce

1. During a previous session, a PowerShell-based Claude installation was aborted mid-process
2. Uninstalled and reinstalled Claude Desktop
3. Launched Cowork — greeted with "Failed to start Claude's workspace" error
4. Killed all Claude/Cowork processes via Task Manager
5. Uninstalled again, deleted all leftover AppData files, reinstalled fresh
6. Same error persists on every launch

Verification Steps Taken

• Confirmed no lingering Claude services or processes before reinstall
• Confirmed no leftover files in AppData\Local\Anthropic, AppData\Roaming\Anthropic, or Program Files\Anthropic
• Enabled HypervisorPlatform via PowerShell and rebooted
• Confirmed CoworkVMService binary exists at expected path
• Confirmed CoworkVMService reaches STATE 4 RUNNING after launch
• Event logs show service is actively logging HVSock and RPC activity but hitting idle timeout due to no active connections from the app

PowerShell Output

sc.exe query CoworkVMService

SERVICE_NAME: CoworkVMService
        TYPE               : 210  WIN32_PACKAGED_PROCESS
        STATE              : 4  RUNNING
        WIN32_EXIT_CODE    : 0  (0x0)
        SERVICE_EXIT_CODE  : 0  (0x0)

Event Log Evidence

CoworkVMService is logging rapid Event ID 1 entries including:

• [HVSock] Reading message
• [RPC] Sending/Receiving requests
• [Server] Session has no active connections, idle timeout starts

This suggests the service starts but the app never successfully establishes a connection to it.

Environment

• OS: Windows 11
• Hardware: HP laptop
• Claude Version: Claude_1.1.6041.0_x64__pzs8sxrjxfjjc
• Virtualization: Hyper-V fully enabled, HypervisorPlatform enabled, VirtualMachinePlatform enabled
• Plan: Claude Max

What Should Happen?

Cowork should successfully connect to CoworkVMService and start the workspace.

Error Messages/Logs

### Expected Behavior
Cowork should successfully connect to CoworkVMService and start the workspace.

### Actual Behavior
App reports "VM service not running" despite service being in STATE 4 RUNNING.

Steps to Reproduce

The issue appears to have started after aborting a mid-process PowerShell installation of Claude. Subsequent clean reinstalls have not resolved the issue, suggesting the problem may be in how the app attempts to connect to the service rather than the service itself.

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

no idea

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

The issue appears to have started after aborting a mid-process PowerShell installation of Claude. Subsequent clean reinstalls have not resolved the issue, suggesting the problem may be in how the app attempts to connect to the service rather than the service itself.