Claude Code / AI Coding Tools
Claude Desktop Cowork Fails to Start Workspace on Windows — VHDX Permission Denied 0x80070005
Fix Claude Code Cowork VM startup failing on Windows due to Hyper-V VHDX disk permission denial when attaching virtual disks Includes evidence for Claude Code troubleshooting demand.
- Category
- AI Coding Tools
- Error signature
Account does not have permission to open attachment 'smol-bin.vhdx'. Error: Access is denied. (0x80070005); HcsWaitForOperationResult failed with HRESULT 0x80070005 (Access is denied); Failed to start Claude's workspace. VM service not running.- Quick fix
- Compare the failing environment with a known working setup, then change one configuration value at a time.
- Updated
What this error means
Account does not have permission to open attachment 'smol-bin.vhdx'. Error: Access is denied. (0x80070005); HcsWaitForOperationResult failed with HRESULT 0x80070005 (Access is denied); Failed to start Claude's workspace. VM service not running. is a Claude Code failure pattern reported for developers trying to fix claude code cowork vm startup failing on windows due to hyper-v vhdx disk permission denial when attaching virtual disks. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.
Why this happens
GitHub issue #61559 in anthropics/claude-code shows CoworkVMService successfully creates the VM session but crashes when Hyper-V attempts to attach VHDX files (smol-bin.vhdx, rootfs.vhdx). User confirmed Hyper-V components enabled, reinstalled multiple times, permissions set correctly. Error 0x80070005 is a classic Windows ACL/Hyper-V isolation issue on new builds. Affects paying Claude Code/Claude Desktop users unable to use Cowork features. Category mapping: AI Coding Tools (Claude Code is an AI coding assistant tool).
Common causes
- GitHub issue #61559 in anthropics/claude-code shows CoworkVMService successfully creates the VM session but crashes when Hyper-V attempts to attach VHDX files (smol-bin.vhdx, rootfs.vhdx). User confirmed Hyper-V components enabled, reinstalled multiple times, permissions set correctly. Error 0x80070005 is a classic Windows ACL/Hyper-V isolation issue on new builds. Affects paying Claude Code/Claude Desktop users unable to use Cowork features. Category mapping: AI Coding Tools (Claude Code is an AI coding assistant tool).
Quick fixes
- Confirm the exact error signature matches
Account does not have permission to open attachment 'smol-bin.vhdx'. Error: Access is denied. (0x80070005); HcsWaitForOperationResult failed with HRESULT 0x80070005 (Access is denied); Failed to start Claude's workspace. VM service not running.. - Check the Claude Code account, local tool state, and provider configuration involved in the failing workflow.
- Compare the failing environment with a known working setup, then change one configuration value at a time.
Platform/tool-specific checks
- Verify the command, editor, extension, or API client that produced the error.
- Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
- Avoid deleting credentials, local model data, or project settings until the failing scope is clear.
Step-by-step troubleshooting
- Capture the exact error message and the command, editor action, or request that triggered it.
- Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
- Review the source evidence below and compare it with your environment.
- Apply one change at a time and rerun the smallest failing action.
- Keep the working fix documented for the team or deployment environment.
How to prevent it
- Keep provider/tool configuration documented.
- Record non-secret diagnostics such as tool version, provider name, model name, and command path.
- Add a lightweight check before CI or production workflows depend on the tool.
Sources checked
Evidence note: GitHub issue #61559 in anthropics/claude-code shows CoworkVMService successfully creates the VM session but crashes when Hyper-V attempts to attach VHDX files (smol-bin.vhdx, rootfs.vhdx). User confirmed Hyper-V components enabled, reinstalled multiple times, permissions set correctly. Error 0x80070005 is a classic Windows ACL/Hyper-V isolation issue on new builds. Affects paying Claude Code/Claude Desktop users unable to use Cowork features. Category mapping: AI Coding Tools (Claude Code is an AI coding assistant tool).
Related errors
- AI Coding Tools
FAQ
What should I check first?
Start with the exact Account does not have permission to open attachment 'smol-bin.vhdx'. Error: Access is denied. (0x80070005); HcsWaitForOperationResult failed with HRESULT 0x80070005 (Access is denied); Failed to start Claude's workspace. VM service not running. text and the smallest action that reproduces it.
Can I ignore this error?
No. Treat it as a failed Claude Code workflow until the root cause is understood.
Is this guaranteed to have one fix?
No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.
How do I know the fix worked?
Rerun the same command, editor action, or request. The fix is working when that action completes without Account does not have permission to open attachment 'smol-bin.vhdx'. Error: Access is denied. (0x80070005); HcsWaitForOperationResult failed with HRESULT 0x80070005 (Access is denied); Failed to start Claude's workspace. VM service not running..