Preflight Checklist

• I have searched existing issues and this hasn't been reported yet
• This is a single bug report (please file separate reports for different bugs)
• I am using the latest version of Claude Code

What's Wrong?

Environment

Cowork consistently fails with:

"Failed to start Claude's workspace — VM service not running. The service failed to start."

Cowork has never successfully completed initialization on this system despite multiple reinstalls, Hyper-V enabling, and manual service start attempts.

Root Cause Analysis

Three interrelated issues identified through diagnostic investigation:

Issue 1: CoworkVMService startup type set to Manual (not Automatic)
CoworkVMService is installed with StartupType: Manual, so it does not start on boot. Attempting to reconfigure via PowerShell fails:

Set-Service CoworkVMService -StartupType Automatic Set-Service: Service 'Claude (CoworkVMService)' cannot be configured due to the following error: Access is denied.

Registry workaround attempted:

reg add "HKLM\SYSTEM\CurrentControlSet\Services\CoworkVMService" /v Start /t REG_DWORD /d 2 /f

Registry write succeeded but service still fails to start after reboot.

Issue 2: WinNAT rule not created on startup
Get-NetNat returns empty after every system start. The app creates the HNS network (cowork-vm-nat) but does NOT create the corresponding WinNAT rule. Without NAT, the VM has no route to the internet and cannot reach api.anthropic.com.
Manually creating the NAT rule:

New-NetNat -Name "cowork-vm-nat" -InternalIPInterfaceAddressPrefix "172.16.0.0/24"

Returns Store: Local — does not persist across reboots.

Issue 3: vEthernet (cowork-vm-nat) adapter never persists
The virtual network adapter required for IP forwarding does not exist at startup:

Set-NetIPInterface -InterfaceAlias "vEthernet (cowork-vm-nat)" -Forwarding Enabled Set-NetIPInterface: No MSFT_NetIPInterface objects found with property 'InterfaceAlias' equal to 'vEthernet (cowork-vm-nat)'.

The adapter appears to require the VM service to be running before it is created — creating a circular dependency: service needs adapter, adapter needs service.

What Should Happen?

Cowork should start successfully and reach api.anthropic.com on Windows 10 Pro with Hyper-V enabled and Claude Desktop installed as Administrator.

Specifically:

• CoworkVMService should be set to Automatic startup during installation
• The installer should create both the HNS network AND the corresponding WinNAT rule on startup
• IP forwarding should be enabled on vEthernet (cowork-vm-nat) automatically
• These networking rules should persist across reboots without manual PowerShell intervention

Error Messages/Logs

From %APPDATA%\Claude\logs\cowork_vm_node.log:

2026-02-19 14:04:22 [info] [VM] Loading vmClient (TypeScript) module...
2026-02-19 14:04:22 [info] [VM] Module loaded successfully
2026-02-19 14:04:22 [info] [warm] Fetching VM hash for version 1.1.3647
2026-02-19 14:04:22 [info] [warm] VM hash for version 1.1.3647: fb30784dadb34104626c8cf6d8f90dd47cd393cc
2026-02-19 14:04:22 [info] [warm] All warm files already exist for SHA fb30784dadb34104626c8cf6d8f90dd47cd393cc
2026-02-19 14:39:32 [info] [Bundle:status] rootfs.vhdx version mismatch: have=0ae58222a1f34cf74c74ce47cc717a82a4eb0f25, want=fb30784dadb34104626c8cf6d8f90dd47cd393cc
2026-02-19 14:39:32 [info] [VM] Loading vmClient (TypeScript) module...
2026-02-19 14:39:32 [info] [VM] Module loaded successfully
2026-02-19 14:39:32 [info] [Bundle:status] rootfs.vhdx version mismatch: have=0ae58222a1f34cf74c74ce47cc717a82a4eb0f25, want=fb30784dadb34104626c8cf6d8f90dd47cd393cc
2026-02-19 14:39:32 [info] [Bundle:status] rootfs.vhdx version mismatch: have=0ae58222a1f34cf74c74ce47cc717a82a4eb0f25, want=fb30784dadb34104626c8cf6d8f90dd47cd393cc
2026-02-19 14:39:32 [info] [downloadVM] Deleting old rootfs.vhdx and cache to free disk space
2026-02-19 14:39:32 [info] [warm] Promoting warm file rootfs.vhdx from C:\Users\guinw\AppData\Roaming\Claude\vm_bundles\warm\fb30784dadb34104626c8cf6d8f90dd47cd393cc\rootfs.vhdx.zst
2026-02-19 14:42:00 [info] [warm] rootfs.vhdx checksum validated
2026-02-19 14:42:00 [info] [warm] rootfs.vhdx promotion completed in 147886ms
2026-02-19 14:42:00 [info] [downloadVM] Promoted rootfs.vhdx from warm bundle
2026-02-19 14:42:00 [info] [Bundle:status] vmlinuz version mismatch: have=0ae58222a1f34cf74c74ce47cc717a82a4eb0f25, want=fb30784dadb34104626c8cf6d8f90dd47cd393cc
2026-02-19 14:42:00 [info] [downloadVM] Deleting old vmlinuz and cache to free disk space
2026-02-19 14:42:00 [info] [warm] Promoting warm file vmlinuz from C:\Users\guinw\AppData\Roaming\Claude\vm_bundles\warm\fb30784dadb34104626c8cf6d8f90dd47cd393cc\vmlinuz.zst
2026-02-19 14:42:01 [info] [warm] vmlinuz checksum validated
2026-02-19 14:42:01 [info] [warm] vmlinuz promotion completed in 318ms
2026-02-19 14:42:01 [info] [downloadVM] Promoted vmlinuz from warm bundle
2026-02-19 14:42:00 [info] [Bundle:status] initrd version mismatch: have=0ae58222a1f34cf74c74ce47cc717a82a4eb0f25, want=fb30784dadb34104626c8cf6d8f90dd47cd393cc
2026-02-19 14:42:01 [info] [downloadVM] Deleting old initrd and cache to free disk space
2026-02-19 14:42:01 [info] [warm] Promoting warm file initrd from C:\Users\guinw\AppData\Roaming\Claude\vm_bundles\warm\fb30784dadb34104626c8cf6d8f90dd47cd393cc\initrd.zst
2026-02-19 14:42:04 [info] [warm] initrd checksum validated
2026-02-19 14:42:04 [info] [warm] initrd promotion completed in 3720ms
2026-02-19 14:42:04 [info] [downloadVM] Promoted initrd from warm bundle
2026-02-19 14:42:04 [info] All files ready in C:\Users\guinw\AppData\Roaming\Claude\vm_bundles\claudevm.bundle
2026-02-19 15:01:00 [info] [VM] Loading vmClient (TypeScript) module...
2026-02-19 15:01:00 [info] [VM] Module loaded successfully

Note: Log terminates after "Module loaded successfully" with no network status entries.

Expected entries (VM Network status: CONNECTED, API reachability: REACHABLE) never appear.

Steps to Reproduce

1. Install Claude Desktop on Windows 10 Pro using standard installer run as Administrator
2. Enable Hyper-V via optionalfeatures
3. Restart computer
4. Open Claude Desktop
5. Click Cowork tab
6. Observe: "Failed to start Claude's workspace — VM service not running"

Suggested Fix - The installer should:

1. Set CoworkVMService StartupType to Automatic (not Manual) with appropriate permissions
2. Create the WinNAT rule (New-NetNat) as part of VM initialization, not just the HNS network
3. Enable IP forwarding on vEthernet (cowork-vm-nat) during VM startup sequence
4. Ensure these networking components are recreated persistently on each boot, not just on first run

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

n/a

Claude Code Version

1.1.3647

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

What Was Tried

• Full uninstall and reinstall as Administrator
• Enabled Hyper-V (Virtual Machine Management and Host Compute services confirmed Running)
• Manually started CoworkVMService via Start-Service CoworkVMService — works temporarily
• Attempted Set-Service CoworkVMService -StartupType Automatic — Access Denied
• Registry edit to set StartupType to Automatic (0x2) — wrote successfully, did not persist behavior
• Manually created WinNAT rule via New-NetNat — created successfully but Store: Local, does not persist
• Attempted IP forwarding on vEthernet adapter — adapter does not exist at startup
• No VPN present
• Confirmed not Windows ARM64

Related Issues

#25155 — Windows 10 Pro Hyper-V NAT routing (identical root cause)
#24945 — Cowork VM boots but API unreachable on Windows
#24918 — Windows 11 Home Hyper-V/WSL2 issue
#25136 — Windows 11 Pro yukonSilver unsupported + CoworkVMService access denied