[BUG] Cowork VM guest connection timeout on Windows 10 Pro — 60s timeout too short for HDD systems, Linux guest stalls after add_plan9_shares

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 every time with "VM connection timeout after 60 seconds" on Windows 10 Pro with a 5400rpm HDD. The VM boots and Plan9 shares mount successfully, but the Linux guest never starts its agent process and calls back within the 60 second window. Reinstalled 5+ times. The issue persists across clean installs.

Environment

• OS: Windows 10 Pro, build 19045, x64
• - Claude Desktop: v1.569.0.0 (MSIX install from claude.com/download)
• - - Plan: Pro
• - - - Hardware: 5400rpm HDD, 16GB RAM

Windows features confirmed enabled

• VirtualMachinePlatform ✅
• - Microsoft-Hyper-V (all components) ✅
• - - Containers-DisposableClientVM (Windows Sandbox) ✅
• - - - HypervisorPlatform ✅

Exact log pattern from cowork_vm_node.log — every attempt:

[VM:steps] vm_boot completed (6346ms)
[VM:steps] add_plan9_shares started
[VM:steps] add_plan9_shares completed (57ms)
[VM:start] Still waiting for guest connection... 10225ms elapsed, 21 polls
[VM:start] Still waiting for guest connection... 20467ms elapsed, 41 polls
[VM:start] Still waiting for guest connection... 30732ms elapsed, 61 polls
[VM:start] Still waiting for guest connection... 40883ms elapsed, 81 polls
[VM:start] Still waiting for guest connection... 51064ms elapsed, 101 polls
[VM:start] Connection timeout, last completed step: add_plan9_shares
[VM:start] Startup failed: Error: VM connection timeout after 60 seconds

SSH log only ever shows "Initialized" — no actual SSH connection into the guest is ever attempted.

Process behavior during hang:

• vmcompute runs throughout
• - vmmem starts at ~484MB and never grows — guest kernel stalls during boot
• - - Disk read activity drops to zero immediately after Plan9 shares mount
• - - - On one attempt, workspace setup progress bar reached 27% before timing out

VM bundle — all files present and correct sizes:

• rootfs.vhdx: 9.49 GB ✅
• - rootfs.vhdx.zst: 2.34 GB ✅
• - - sessiondata.vhdx: 507 MB ✅
• - - - smol-bin.vhdx: 37 MB ✅
• - - - - vmlinuz, initrd: present ✅

What does NOT fix it:

• Reinstalling Claude Desktop (attempted 5+ times)
• - Enabling Windows Sandbox
• - - Enabling HypervisorPlatform
• - - - Clearing all app data and caches
• - - - - Multiple reboots

Root cause hypothesis:
Two likely contributing factors:

1. The Linux guest kernel boots but stalls before starting the Claude guest agent. vmmem stops growing and disk activity drops to zero, suggesting a kernel-level stall inside the VM.
2. 2. The 60 second timeout is too short for HDD systems. The system requirements for Cowork do not specify an SSD, leaving HDD users with no warning and no workaround.

Feature request within this bug: Please increase the guest connection timeout or make it configurable. 120-180 seconds minimum would allow HDD systems to complete VM boot.

Related issues:

• #37312 — Cowork hangs on "Setting up Claude's workspace"
• - #32169 — VM download_and_sdk_prepare hangs indefinitely
• - - #29848 — Cowork completely unusable on Windows

What Should Happen?

Cowork should either boot the VM successfully within a longer timeout window, or display a clear error message indicating that an SSD is required. The 60 second timeout should be increased to at least 120-180 seconds, or made configurable, to support HDD systems. The system requirements page should be updated to list SSD as a requirement if the current timeout cannot be changed.

Error Messages/Logs

2026-04-05 14:55:30 [info] [VM:start] Beginning startup
2026-04-05 14:55:33 [info] [VM:steps] vm_boot started
2026-04-05 14:55:39 [info] [VM:steps] vm_boot completed (6346ms)
2026-04-05 14:55:39 [info] [VM:steps] add_plan9_shares started
2026-04-05 14:55:39 [info] [VM:steps] add_plan9_shares completed (57ms)
2026-04-05 14:55:49 [info] [VM:start] Still waiting for guest connection... 10225ms elapsed, 21 polls
2026-04-05 14:56:00 [info] [VM:start] Still waiting for guest connection... 20467ms elapsed, 41 polls
2026-04-05 14:56:10 [info] [VM:start] Still waiting for guest connection... 30732ms elapsed, 61 polls
2026-04-05 14:56:20 [info] [VM:start] Still waiting for guest connection... 40883ms elapsed, 81 polls
2026-04-05 14:56:30 [info] [VM:start] Still waiting for guest connection... 51064ms elapsed, 101 polls
2026-04-05 14:56:39 [error] [VM:start] Connection timeout, last completed step: add_plan9_shares
2026-04-05 14:56:39 [error] [VM:start] Startup failed: Error: VM connection timeout after 60 seconds

Steps to Reproduce

1. Install Claude Desktop v1.569.0.0 on Windows 10 Pro (build 19045) with a 5400rpm HDD
2. Enable VirtualMachinePlatform, Hyper-V, Windows Sandbox, and HypervisorPlatform via PowerShell
3. Sign in with Pro plan
4. Click the Cowork tab
5. Submit any task
6. Observe: "Failed to start Claude's workspace — VM connection timeout after 60 seconds"

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Sonnet 4.6

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_