[BUG] [BUG] Claude Desktop installer fails with HRESULT 0x80073CF6 - MSIX package stuck in wedged state

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?

Claude Desktop cannot be reinstalled. The installer fails with "AddPackage failed with HRESULT 0x80073CF6". Two old package folders (versions 1.4758.0.0 and 1.5220.0.0) remain stuck in C:\Program Files\WindowsApps\ and cannot be deleted even with administrator ownership. No standard tool detects the package as installed (Get-AppxPackage, winget, DISM all return nothing), yet AddPackage fails because the package family name is still claimed. This matches issue #49917.

What Should Happen?

The installer should detect and remove stuck package registrations before attempting AddPackage, or provide a cleanup tool for this scenario.

Error Messages/Logs

Installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF6

cowork_vm_node.log:
[error] [VM:start] Startup failed: Error: failed to set VHDX path: VHDX file not found: C:\Users\usuario\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Local\Claude\vm_bundles\claudevm.bundle\rootfs.vhdx
[info] [VM:start] Skipping auto-reinstall (already attempted once)

Stuck folders in WindowsApps (cannot delete even with takeown + icacls):
C:\Program Files\WindowsApps\Claude_1.4758.0.0_x64__pzs8sxrjxfjjc
C:\Program Files\WindowsApps\Claude_1.5220.0.0_x64__pzs8sxrjxfjjc

Steps to Reproduce

1. Uninstall Claude Desktop via Settings > Apps
2. Delete AppData folders manually
3. Run Claude installer as Administrator
4. Installer fails with HRESULT 0x80073CF6
5. Get-AppxPackage, winget, DISM — none detect the package
6. Old package folders remain in WindowsApps with access denied

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

1.6259.1 (5095e7)

Platform

Other

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

This is Claude Desktop (Cowork), not Claude Code. Related to known issue #49917. Support ticket also filed via support.anthropic.com.