[BUG] Cowork fails with 0x800703ed when VeraCrypt encrypted drive is present (Plan9 share)

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?

When a VeraCrypt-encrypted drive is present but not mounted/decrypted (filesystem shows as unrecognized/RAW), Cowork attempts to add it as a Plan9 share and fails with HRESULT 0x800703ed (ERROR_NOT_ALL_ASSIGNED). The VM crashes at the add_plan9_shares step.

Error from cowork-service.log:

[VM] Adding Plan9 share via HcsModifyComputeSystem: name=d path=D:\ port=9903 flags=0x10 hasToken=true
[HCS] HcsModifyComputeSystem returned: hr=0x0, lastErr=The operation completed successfully.
[HCS] Modify result: {"Error":-2147023891,"ErrorMessage":""}
[VM] Failed to add Plan9 share 'd': HcsWaitForOperationResult failed with HRESULT 0x800703ed: {"Error":-2147023891,"ErrorMessage":""}

What Should Happen?

Cowork should skip drives with unrecognized or inaccessible filesystems (e.g. VeraCrypt volumes that are not yet mounted/decrypted) instead of crashing. The error should be gracefully handled and the workspace should start normally without the inaccessible drive being shared.

Error Messages/Logs

[VM] Adding Plan9 share via HcsModifyComputeSystem: name=d path=D:\ port=9903 flags=0x10 hasToken=true
[HCS] Calling HcsModifyComputeSystem
[HCS] HcsModifyComputeSystem returned: hr=0x0, lastErr=The operation completed successfully.
[HCS] Modify result: {"Error":-2147023891,"ErrorMessage":""}
[VM] Failed to add Plan9 share 'd': HcsWaitForOperationResult failed with HRESULT 0x800703ed: {"Error":-2147023891,"ErrorMessage":""}
[VNet] Virtual network stopped
[RPC] Server stopped

Steps to Reproduce

1. Install VeraCrypt and create an encrypted volume on a drive (e.g. D:\)
2. Leave the drive NOT mounted/decrypted (filesystem will appear as unrecognized/RAW to Windows)
3. Open Claude Desktop
4. Click on the Cowork tab
5. Observe the error: "Failed to start Claude's workspace — failed to add Plan9 share 'd': HcsWaitForOperationResult failed with HRESULT 0x800703ed"

Workaround: Remove the drive letter from the encrypted volume (via diskpart or Remove-PartitionAccessPath), then manually start CoworkVMService before launching Claude Desktop. When VeraCrypt mounts the volume later, it uses a different drive letter and Cowork works fine.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

N/A (Claude Desktop v1.1062.0.0)

Claude Code Version

Windows 11

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

This issue affects users with VeraCrypt (or similar disk encryption tools) where the raw encrypted volume has a drive letter assigned but is not yet decrypted/mounted. The Cowork VM service should gracefully skip inaccessible drives rather than crashing the entire workspace startup.