[BUG] Claude Desktop Cowork on Windows fails to start VM with HCS 0x80070003

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?

Title:
[BUG] Claude Desktop Cowork on Windows fails to start VM with HCS 0x80070003 (Synthetic Storage path-not-found)

Description:

Preflight Checklist

• I have searched existing issues
• This is a single bug report
• I am using the latest Claude Desktop version available to me

What's Wrong?

Claude Desktop Cowork on Windows fails to start the workspace VM on a clean install.

The app downloads and prepares the VM bundle successfully, but VM boot fails every time with:

HCS operation failed: failed to start VM
HRESULT 0x80070003
Synthetic Storage
"The system cannot find the path specified"

Environment

• OS: Windows 11
• App: Claude Desktop (MSIX / Store-style install)
• Claude Desktop version observed in logs: 1.1617.0.0
• Hyper-V related services running: vmms, vmcompute, hns
• Automount was enabled during troubleshooting

What Should Happen?

Cowork should create and boot the workspace VM successfully.

Steps to Reproduce

1. Install Claude Desktop on Windows.
2. Open the Cowork tab.
3. Select a local project folder.
4. Start workspace setup.
5. Wait for VM bundle download and setup to complete.
6. VM boot fails with HCS 0x80070003.

Error Message

Failed to start Claude's workspace

HCS operation failed: failed to start VM: HcsWaitForOperationResult failed with HRESULT 0x80070003

Hyper-V Worker Admin shows:

• Event ID 12030
• Event ID 12010
• Synthetic Storage
• "The system cannot find the path specified"

Important Findings

During troubleshooting, the VM bundle files were successfully downloaded and present, including:

• rootfs.vhdx
• sessiondata.vhdx
• smol-bin.vhdx
• vmlinuz
• initrd

The log also showed that Claude granted VM access to these files successfully.

Example paths observed:

• C:\Users\Uzivatel\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\vm_bundles\claudevm.bundle\rootfs.vhdx
• ...\sessiondata.vhdx
• ...\smol-bin.vhdx
• ...\vmlinuz
• ...\initrd

However, VM boot still fails immediately afterward with Synthetic Storage path-not-found.

Another important finding:
Claude previously referenced %APPDATA%\Claude\vm_bundles\claudevm.bundle while the actual files were initially under the MSIX package LocalCache\Roaming\Claude path. Even after correcting that mismatch and also testing a full clean reinstall, the issue persisted.

Troubleshooting Already Performed

• Restarted PC multiple times
• Reinstalled workspace
• Full uninstall and purge of Claude Desktop MSIX package and user data
• Clean reinstall
• Verified Hyper-V services are running
• Verified VM bundle files exist
• Enabled automount
• Tested corrected Roaming/AppData path handling
• Tested with physically copied bundle data instead of junction/symlink approach

Conclusion

This appears to be a Claude Desktop Cowork Windows bug in VM configuration / storage attachment / HCS path handling, rather than a local Hyper-V setup problem.

The VM bundle is created and accessible, but the VM definition or storage mapping passed to Hyper-V appears invalid, causing boot to fail before the guest OS actually starts.

Logs

I can provide:

• cowork_vm_node.log
• Hyper-V Worker Admin event log entries
• screenshots of the exact HCS error

What Should Happen?

Claude Desktop Cowork on Windows should create and boot the workspace VM successfully and open the selected project without any HCS or Hyper-V storage errors.

Error Messages/Logs

Failed to start Claude's workspace

HCS operation failed: failed to start VM: HcsWaitForOperationResult failed with HRESULT 0x80070003

Hyper-V Worker Admin events:
- Event ID 12030
- Event ID 12010
- Synthetic Storage
- The system cannot find the path specified

Relevant finding from cowork_vm_node.log:
- VM bundle files are downloaded successfully
- Claude grants VM access to rootfs.vhdx, sessiondata.vhdx, smol-bin.vhdx, vmlinuz, and initrd
- VM boot still fails immediately afterward with Synthetic Storage path-not-found

Important note:
Claude previously referenced %APPDATA%\Claude\vm_bundles\claudevm.bundle while actual bundle files were under the MSIX package path:
C:\Users\Uzivatel\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\vm_bundles\claudevm.bundle

Even after a full uninstall, purge, clean reinstall, and additional path testing, the issue persists.

Steps to Reproduce

1. Install Claude Desktop on Windows.
2. Open the Cowork tab.
3. Choose any local project folder.
4. Start workspace setup.
5. Wait for the VM bundle download and setup to complete.
6. Claude fails to start the workspace VM with HCS HRESULT 0x80070003.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude Desktop 1.1617.0.0

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_