[BUG] Claude Cowork sandbox never becomes ready on Windows ARM64 / Snapdragon X Plus

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?

Device: Surface Pro 12-inch / Windows ARM64
CPU: Snapdragon X Plus (8-core) @ 3.30 GHz
CPU manufacturer: Qualcomm Technologies Inc
OS: Windows 11 Home, build 26200
Claude Desktop: 1.11187.1.0 arm64
Claude package: Claude_1.11187.1.0_arm64__pzs8sxrjxfjjc

Claude Cowork chat opens normally, but the Cowork sandbox never becomes ready.

When I ask Cowork to run a simple command such as:

echo hello

the command does not run. The output is always:

Workspace still starting. The isolated Linux environment is booting in the background (usually 10-30 seconds). Try again shortly.

Waiting several minutes does not fix it. Retrying does not fix it. I also sometimes see:

VM connection timeout after 60 seconds

The Windows/HCS VM appears to start successfully, but the Linux guest / sandbox daemon never connects back to the host.

What Should Happen?

Claude Cowork should successfully start the isolated Linux sandbox/VM and allow commands to run inside the selected workspace.

A simple command like:

echo hello

should execute successfully and return:

hello

Claude should also be able to create and run a simple Python file in the workspace without the sandbox staying in a "Workspace still starting" state.

Error Messages/Logs

Command output in Claude Cowork:

Workspace still starting. The isolated Linux environment is booting in the background (usually 10-30 seconds). Try again shortly.

Sometimes the UI also shows:

Failed to start Claude's workspace
VM connection timeout after 60 seconds

Relevant cowork_vm_node.log:

[VM:start] Beginning startup
[VM:steps] download_and_sdk_prepare completed
[VM:steps] load_swift_api completed
[VM:steps] create_network completed
[VM:steps] create_vm_config completed
[VM:steps] vm_boot completed
[VM:steps] add_plan9_shares completed

[VM:start] Still waiting for guest connection... 10193ms elapsed
[VM:start] Still waiting for guest connection... 20381ms elapsed
[VM:start] Still waiting for guest connection... 30568ms elapsed
[VM:start] Still waiting for guest connection... 40809ms elapsed
[VM:start] Still waiting for guest connection... 50964ms elapsed

[VM:start] Connection timeout, last completed step: add_plan9_shares
Dispatching startup error: VM connection timeout after 60 seconds
[VM:start] Startup failed: Error: VM connection timeout after 60 seconds

Relevant cowork-service.log:

[HCS] HcsCreateComputeSystem returned: hr=0x0
[HCS] HcsStartComputeSystem returned: hr=0x0
[HVSock] Listening on port 51234
[RPC] Server started, waiting for sdk-daemon connection on port 51234
[VNet] Listening for VM network connections on vsock port 1024
[VM] Adding Plan9 share via HcsModifyComputeSystem: name=c path=C:\
[VM] Adding Plan9 share via HcsModifyComputeSystem: name=d path=D:\
[VM] VM started successfully

The Windows/HCS VM appears to start successfully, but the Linux guest / sdk-daemon never connects back to the host.

Steps to Reproduce

1. Use a Windows ARM64 device with Snapdragon X Plus.
2. Install Claude Desktop ARM64.
3. Open Claude Desktop and go to Claude Cowork.
4. Create or open a clean workspace, for example:

C:\Users\<user>\Claude\Projects\TEST COWORK

1. Ask Claude Cowork to run exactly one command:

echo hello

1. The command does not run. Instead, it returns:

Workspace still starting. The isolated Linux environment is booting in the background (usually 10-30 seconds). Try again shortly.

1. Wait several minutes and try again. The same message appears.
2. The issue also reproduces after restarting Windows and after resetting the Cowork VM bundle folders.

Claude Model

Sonnet (default)

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.165 bundled with Claude Desktop/Cowork

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

This is not using a globally installed Claude CLI. The claude command is not available in PATH.

Bundled versions found under Claude Desktop/Cowork data directory:

• Bundled Claude Code: 2.1.165
• Bundled Claude Code VM: 2.1.165
• Claude Desktop package: Claude_1.11187.1.0_arm64__pzs8sxrjxfjjc

Hardware:

• CPU: Snapdragon X Plus (8-core) @ 3.30 GHz
• Manufacturer: Qualcomm Technologies Inc
• CPU architecture: ARM64 / WMI Architecture 12
• OS: Windows 11 Home ARM64, build 26200

I tested a clean workspace on C: and also an existing workspace on D:. Both reproduce the same issue.

I already tried:

• Restarting Claude Desktop
• Restarting Windows
• Enabling HypervisorPlatform, VirtualMachinePlatform, and WSL
• Confirming CoworkVMService, hns, and vmcompute are running
• Confirming the HCS VM is running via hcsdiag list
• Renaming/resetting vm_bundles, claude-code-vm, and local-agent-mode-sessions
• Letting Claude re-download/recreate the VM bundle

The issue still reproduces after all of the above.