[BUG] Claude Desktop white/blank screen after update on Windows 10, MSIX AddPackage 0x80073CF6 during install

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?

After installing/updating Claude Desktop on Windows 10 (build 19045), the app window opens but shows a completely white/blank screen — no UI content renders at all. This started right after updating to the latest version.

Prior to the white screen, I also hit an MSIX installation failure during a reinstall attempt:
AddPackage failed with HRESULT 0x80073CF6

The install log showed a conflicting CoworkVMService that couldn't be removed ("Access is denied"), which appears to have left the package in a partially-registered state before the white screen issue began.

What Should Happen?

Claude Desktop should render its UI normally after install/update, and the installer should be able to cleanly recover from a conflicting/wedged CoworkVMService instead of leaving the package in a broken state.

Error Messages/Logs

2026/07/03 10:56:37.896437 MSIX installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF6
2026/07/03 10:56:37.896458 ERROR dialog (opening log): Installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF6

2026/07/03 10:37:23.875505 Removing conflicting CoworkVMService...
2026/07/03 10:37:23.875505 WARNING: failed to remove conflicting service: could not open CoworkVMService: Access is denied.

Steps to Reproduce

1. Have Claude Desktop already installed on Windows 10 with CoworkVMService running
2. Run the latest Claude Desktop installer to update
3. Installer attempts to remove conflicting CoworkVMService, fails with "Access is denied"
4. AddPackage fails with HRESULT 0x80073CF6
5. Even after eventual successful install, app opens to a completely white/blank screen — no UI renders
6. Killing all Claude processes via Task Manager and relaunching does not fix it

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

N/A — this is Claude Desktop, not Claude Code CLI

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Terminal.app (macOS)

Additional Information

Install method: MSIX (official installer from claude.com/download)
Package family name: Claude_pzs8sxrjxfjjc