[BUG] Claude Desktop MSIX install fails with HRESULT 0x80073CF9 due to CoworkVMService conflict (Windows 10 Pro 19045) — recurring after app hangs

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 MSIX install fails with HRESULT 0x80073CF9, related to but
distinct from issue #40682 (locked) — same error code, different environment:
standard Windows 10 Pro, build 19045 (not Canary/AtlasOS), Intel Core i3-4150,
no Hyper-V or debloat involved.

This is a recurring problem: the app has broken with "There is a problem with
Claude. Please reinstall..." three times over the past week (13 Jul, and twice
on 20 Jul).

Windows Reliability Monitor (perfmon /rel) shows the likely trigger:
2026-07-20 10:33:07 — Source: Claude — "Stopped responding and was closed"
(Critical), occurring ~1 second before a CoworkVMService reinstall event in
the System log. This suggests the app hangs during normal use, gets
force-closed by Windows, and that abrupt termination leaves the MSIX
package/service in an inconsistent state.

What Should Happen?

Claude Desktop installs successfully on Windows Canary 26200.

Error Messages/Logs

AddPackage fails instantly (~250ms) every time with HRESULT 0x80073CF9. The installer never gets past the "Evaluated state handler" check. The error dialog that should offer "install without Cowork" does not appear.

Relevant log excerpt:
Installing via AddPackage (current-user)...
MSIX installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF9
ERROR dialog (with log path): Administrator access is required to install Claude with full features. You can try again or install without Cowork.

Steps to Reproduce

Steps to Reproduce

1. Install Claude Desktop on Windows Canary build 26200 with AtlasOS debloat applied
2. Install fails, leaving a ghost PackageFamily entry in StateRepository with no corresponding Package
3. Every subsequent install attempt fails identically with 0x80073CF9
4. Rebooting, clearing temp files, removing AppxPackage, deleting WindowsApps folders, and manually replacing StateRepository-Machine.srd all fail to resolve 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 bug is with the Claude Desktop installer (ClaudeSetup.exe), not Claude Code CLI. Unable to install Claude Desktop to obtain a version.

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

OS: Windows 10.0.26200 (Insider Canary channel)
Debloat: AtlasOS applied
Architecture: x64 (AMD Ryzen 7800X3D)
Claude installer version: 1.1.8629
SHA256: 1d0e38aaf371de09f4102d1f9504cdde4c314247b07aa3f068e17f573be1f16e
All MSIX services running: AppXSvc, StateRepository, ClipSVC, AppReadiness
Sideloading: enabled
S Mode: false
Developer Mode: not required (sideloading already enabled)