[BUG] [Cowork] Windows Home: "VM service not running" when HypervisorPlatform is disabled — no preflight check, restart/reinstall guidance ineffective

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 its workspace VM with the error: "Failed to start Claude's workspace — VM service not running. The service failed to start." The error suggests restarting Claude or the computer, and reinstalling the workspace. None of these work, because the actual root cause is at the Windows feature level: the HypervisorPlatform optional feature was Disabled on my machine.

Cowork was previously working on this machine, so the feature was either disabled by a Windows update or a Claude Desktop update changed which virtualization backend Cowork requires. I did not change any virtualization settings myself.

Diagnostics performed (via Claude Code on the host):

• CoworkVMService: Stopped (would not start)
• vmms service: does not exist (Windows Home — full Hyper-V unavailable on this edition)
• %APPDATA%\Claude\logs\cowork_vm_node.log: repeated "[vm-client] Event resubscribe failed: Error: connect ENOENT \\.\pipe\cowork-vm-service"
• Get-NetNat: fails with "Invalid class" (NAT infrastructure unavailable)
• Get-WindowsOptionalFeature: HypervisorPlatform = Disabled, VirtualMachinePlatform = Enabled
• Task Manager: CPU Virtualization = Enabled (Intel VT-x active in BIOS)

Confirmed fix:
Enable-WindowsOptionalFeature -Online -FeatureName HypervisorPlatform -All

• reboot. After this, CoworkVMService starts and runs, the workspace rebuilds, and Cowork works normally.

The product issues:

1. No preflight check: Cowork attempts VM startup without verifying HypervisorPlatform is enabled, then surfaces a generic error.
2. Misleading guidance: the error recommends restart/reinstall, which cannot fix a missing virtualization prerequisite. I lost significant time following it.
3. "Reinstall the workspace" completes "successfully" without validating the virtualization environment, giving false hope.

Expected behavior:
Cowork (or the workspace installer) should detect that HypervisorPlatform is disabled and show an actionable message, e.g. "Windows Hypervisor Platform is not enabled. Run [command] as Administrator and restart" — or offer to enable it.

Steps to reproduce:

1. Windows 11 Home with HypervisorPlatform disabled (VirtualMachinePlatform enabled, VT-x on in BIOS)
2. Open Claude Desktop → Cowork
3. Observe "VM service not running" error
4. Restart app, reboot, reinstall workspace → error persists
5. Enable HypervisorPlatform + reboot → Cowork works

Environment:

• Windows 11 Home [paste exact version/build from winver]
• Claude Desktop [paste version from Settings → About]
• CPU: Intel Core i7-1065G7 (VT-x enabled)

Related (similar symptoms, different root cause/complaint): #31991, #32233, #27384, #45883, #64258. Unlike those, my failure was fully resolved by enabling HypervisorPlatform. Notably, #64258 shows Cowork has a HYPERVISOR_VIRT_DISABLED detection path — but on my system (WHP disabled, VMP enabled, Win 11 Home) that detection never fired; I received only the generic "VM service not running" error with restart/reinstall guidance.

What Should Happen?

Cowork (or the workspace installer) should preflight-check Windows virtualization prerequisites before attempting VM startup. If HypervisorPlatform is disabled, it should surface an actionable error, e.g.:

"Windows Hypervisor Platform is not enabled. Run the following in an elevated PowerShell, then restart: Enable-WindowsOptionalFeature -Online -FeatureName HypervisorPlatform -All"

— or offer to enable it. The current generic "VM service not running" error with restart/reinstall guidance cannot resolve this root cause and cost me significant troubleshooting time. Additionally, "Reinstall the workspace" should validate the virtualization environment rather than completing "successfully" while the prerequisite is still missing.

Error Messages/Logs

Cowork UI:
Failed to start Claude's workspace
VM service not running. The service failed to start. Restarting Claude or your computer sometimes resolves this. If it persists, you can reinstall the workspace or share your debug logs to help us improve.

%APPDATA%\Claude\logs\cowork_vm_node.log (repeating):
2026-06-10 12:09:53 [warn] [vm-client] Event resubscribe failed: Error: connect ENOENT \\.\pipe\cowork-vm-service
2026-06-10 12:09:54 [warn] [vm-client] Event resubscribe failed: Error: connect ENOENT \\.\pipe\cowork-vm-service
(continues every ~1 second)

Get-NetNat: "Invalid class" (HRESULT 0x80041010)
Get-Service CoworkVMService: Stopped
Get-Service vmms: service does not exist (Windows Home)
Get-WindowsOptionalFeature: HypervisorPlatform = Disabled, VirtualMachinePlatform = Enabled

Steps to Reproduce

1. Windows 11 Home machine with HypervisorPlatform optional feature Disabled (VirtualMachinePlatform Enabled, Intel VT-x enabled in BIOS — Task Manager shows Virtualization: Enabled)
2. Open Claude Desktop → Cowork tab
3. Observe error: "Failed to start Claude's workspace — VM service not running"
4. Follow the error's guidance: restart Claude, reboot the computer, reinstall the workspace via the in-app link → error persists in all cases; workspace reinstall completes without flagging the missing prerequisite
5. Run in elevated PowerShell: Enable-WindowsOptionalFeature -Online -FeatureName HypervisorPlatform -All
6. Restart the computer
7. CoworkVMService now starts (Status: Running), workspace rebuilds, Cowork fully functional

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.0.42 (CLI, used for diagnostics) — bug is in Claude Desktop / Cowork. Desktop version: [Settings → About in the Claude app]

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

• Windows 11 Home, Version/Build: [from winver]
• Claude Desktop: [version from Settings → About]
• Claude Code CLI 2.0.42 (used on the host to diagnose)
• CPU: Intel Core i7-1065G7, VT-x enabled (Task Manager: Virtualization: Enabled)
• Cowork previously worked on this machine; HypervisorPlatform was found Disabled with no changes made by me — likely disabled by a Windows update or a Desktop update changed backend requirements
• In-app "reinstall the workspace" was attempted and completed without detecting the missing prerequisite