[BUG] Cowork fails with Plan9 share 'h' HRESULT 0x80070005 - MSIX install + OneDrive reparse points (Windows 11 Pro)

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 every time with the error:

Failed to start Claude's workspace
failed to add Plan9 share 'h': HcsWaitForOperationResult failed with HRESULT 0x80070005: {"Error":-2147024891,"ErrorMessage":""}

The VM boots successfully but fails at the add_plan9_shares step. This started occurring and has never worked on this machine. Reinstall and reboot do not resolve it.

Environment:

• OS: Windows 11 Pro
• Claude Desktop version: 1.1617.0.0
• Install type: MSIX (Microsoft Store / WindowsApps), package: Claude_pzs8sxrjxfjjc
• Two OneDrive reparse points present directly in home directory (C:\Users\tturn\OneDrive and C:\Users\tturn\OneDrive - First Choice IT Group)
• External USB drives connected
• VM bundles path: C:\Users\tturn\AppData\Roaming\Claude\vm_bundles (note: different from MSIX LocalCache path)

What Should Happen?

Cowork workspace starts successfully and the Plan9 home directory share mounts without error.

Error Messages/Logs

From cowork_vm_node.log:

2026-04-11 15:09:18 [info] [VM:start] Beginning startup, bundlePath=C:\Users\tturn\AppData\Roaming\Claude\vm_bundles\claudevm.bundle
2026-04-11 15:09:18 [info] [VM:start] Bundle version: 5680b11bcdab215cccf07e0c0bd1bd9213b0c25d
2026-04-11 15:09:19 [info] [VM:steps] vm_boot started
2026-04-11 15:09:20 [info] [VM:steps] vm_boot completed (477ms)
2026-04-11 15:09:20 [info] [VM:steps] add_plan9_shares started
2026-04-11 15:09:20 [error] [VM:start] VM boot failed: failed to add Plan9 share 'h': HcsWaitForOperationResult failed with HRESULT 0x80070005: {"Error":-2147024891,"ErrorMessage":""}
2026-04-11 15:09:20 [info] [VM:start] Skipping auto-reinstall (already attempted once)

Steps to Reproduce

1. Install Claude Desktop via Microsoft Store (MSIX) on Windows 11 Pro
2. Have two OneDrive reparse points present in home directory (personal OneDrive + work OneDrive - both show as ReparsePoint in PowerShell)
3. Have external USB drives connected
4. Click the Cowork tab in Claude Desktop
5. Error appears immediately after VM boots - fails at add_plan9_shares step

Workarounds attempted (none resolved the issue):

• Restart Claude and reboot computer (multiple times)
• Use "Reinstall workspace" button in UI
• icacls on MSIX vm_bundles path: icacls "%LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\vm_bundles" /grant "SYSTEM:F" /T
• icacls on full user profile: icacls "C:\Users\tturn" /grant "SYSTEM:(OI)(CI)(RX)" /T
• Paused OneDrive sync
• Disconnected external drives (partial test)

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

1.1617.0.0 (Claude Desktop, MSIX)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Suspected root cause: The MSIX app container sandbox + two OneDrive reparse points (ReparsePoint attribute) in the home directory (C:\Users\tturn) prevent the HCS Plan9 share mount. The home directory contains virtual filesystem junctions for OneDrive that the Plan9 sharing protocol cannot traverse.

Home directory reparse points confirmed via PowerShell:

• C:\Users\tturn\OneDrive — ReadOnly, Directory, Archive, ReparsePoint
• C:\Users\tturn\OneDrive - First Choice IT Group — ReadOnly, Directory, Archive, ReparsePoint

Related issues: #38188, #43290, #25293

OS: Windows 11 Pro
Platform: Anthropic API (Claude Pro subscription)
Install: MSIX via Microsoft Store (not EXE installer)