[BUG] Claude Desktop installation fails with HRESULT 0x80073CFF on Windows 11

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?

Installation keeps failing on Windows 11 Professional (version 10.0.26200, x64) with error:

ClaudeSetup.log

HRESULT 0x80073CFF. Sideloading is enabled, Developer Mode is on, no previous Claude installation found.

What Should Happen?

Claude Desktop should install successfully on Windows 11 Professional without errors.

Error Messages/Logs

Installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CFF
Windows edition: Professional
Windows version: 10.0.26200
Native arch: x64
Sideloading enabled: true
Developer Mode: enabled
S Mode: false

Steps to Reproduce

1. Download Claude Desktop installer from claude.ai/download (Windows x64)
2. Right-click installer and select "Run as administrator"
3. Installer downloads the MSIX file successfully
4. Installation fails with HRESULT 0x80073CFF

Note: Developer Mode is enabled, no previous Claude installation exists, Windows App Runtime is up to date.

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

N/A

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

_No response_