[BUG] Cowork ARM64: VM boots but guest never connects — "VM connection timeout after 60 seconds

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 on Windows ARM64 fails to start. The VM boots successfully, network creates, Plan9 shares are added, but the guest OS inside smol-bin.arm64.vhdx never establishes a connection back to the host. Times out after 60 seconds every attempt.
This is on the newly released ARM64 Cowork build

Environment

OS: Windows 11 Pro, Build 26200 (upgraded from Home specifically for Cowork)
Architecture: ARM64 (Lenovo, Snapdragon)
Claude Desktop version: 1.1.8629.0
Install method: MSIX (manually installed via Add-AppxPackage — the exe installer kept falling back to Squirrel)
Hyper-V: Enabled (full Microsoft-Hyper-V, not just VirtualMachinePlatform)
Developer Mode: Enabled
Services running: vmms (Hyper-V Virtual Machine Management) ✅, CoworkVMService ✅

What Should Happen?

Cowork workspace starts and is usable.

Error Messages/Logs

2026-03-24 18:52:24 [info] [VM:start] Beginning startup, bundlePath=C:\Users\parmb\AppData\Roaming\Claude\vm_bundles\claudevm.bundle
2026-03-24 18:52:24 [info] [VM:start] Bundle version: fb30784dadb34104626c8cf6d8f90dd47cd393cc
2026-03-24 18:52:24 [info] [VM:start] Copying smol-bin.arm64.vhdx to bundle: C:\Program Files\WindowsApps\Claude_1.1.8629.0_arm64__pzs8sxrjxfjjc\app\resources\smol-bin.arm64.vhdx -> C:\Users\parmb\AppData\Roaming\Claude\vm_bundles\claudevm.bundle\smol-bin.vhdx
2026-03-24 18:52:24 [info] [VM:start] smol-bin.arm64.vhdx copied successfully
2026-03-24 18:52:24 [info] [VM:start] Configuring Windows VM service...
2026-03-24 18:52:25 [info] [VM:start] Windows VM service configured
2026-03-24 18:52:25 [info] [VM:steps] create_network completed (8ms)
2026-03-24 18:52:25 [info] [VM:steps] create_vm_config completed (51ms)
2026-03-24 18:52:25 [info] [VM:steps] vm_boot completed (113ms)
2026-03-24 18:52:25 [info] [VM:steps] add_plan9_shares completed (6ms)
2026-03-24 18:52:35 [info] [VM:start] Still waiting for guest connection... 10174ms elapsed, 21 polls
2026-03-24 18:52:45 [info] [VM:start] Still waiting for guest connection... 20348ms elapsed, 41 polls
2026-03-24 18:52:55 [info] [VM:start] Still waiting for guest connection... 30532ms elapsed, 61 polls
2026-03-24 18:53:06 [info] [VM:start] Still waiting for guest connection... 40704ms elapsed, 81 polls
2026-03-24 18:53:16 [info] [VM:start] Still waiting for guest connection... 50867ms elapsed, 101 polls
2026-03-24 18:53:25 [error] [VM:start] Connection timeout, last completed step: add_plan9_shares
2026-03-24 18:53:25 [error] [VM:start] Startup failed: Error: VM connection timeout after 60 seconds

Steps to Reproduce

Steps to Reproduce

Install Claude Desktop ARM64 as MSIX package
Open Claude Desktop, click Cowork tab
Observe "Starting Claude's workspace..." indefinitely
Workspace never starts

Claude Model

Not sure / Multiple models

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

claude desktop Claude 1.1.8629 (befdfc) 2026-03-24T22:13:01.000Z

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Earlier attempts also showed EBUSY: resource busy or locked on the vhdx file, but this resolved after killing stale processes. The timeout persists regardless.
Multiple clean installs attempted (full removal of AppData, MSIX package, CoworkVMService). Same result every time.
The exe installer from claude.com/download always installs as Squirrel on ARM64, never MSIX. Had to manually download the MSIX via https://claude.ai/api/desktop/win32/arm64/msix/latest/redirect and install with Add-AppxPackage.