[BUG] Cowork fails to install on Windows 11 Pro – HRESULT 0x80073CF6

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?

Environment:

OS: Windows 11 Professional (build 10.0.26200, x64)
Claude Desktop App: latest version (installed April 16, 2026)
Elevation: Full administrator privileges confirmed

Description:
Claude desktop app installs successfully but Cowork fails to install every time with AddPackage failed with HRESULT 0x80073CF6. This occurs even when running the installer with full administrator privileges (elevation type: Full confirmed in logs).
Steps to Reproduce:

Download Claude desktop installer from claude.ai
Run installer as Administrator
Claude installs successfully
Cowork component fails silently — not present in app after install

Troubleshooting Already Attempted:

Ran installer as Administrator (elevation confirmed in logs)
Re-registered Windows DesktopAppInstaller via admin PowerShell
Removed Claude AppX package fully (Get-AppxPackage Claude | Remove-AppxPackage) and reinstalled
Cleared Windows Store cache (wsreset.exe)
Restarted PC between attempts
Attempted install 4+ times — Claude succeeds every time, Cowork fails every time

Relevant Log Output:
Elevation type: Full
Is elevated: true
Installing via AddPackage (current-user)...
MSIX installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF6
Elevation failed: elevated installer exited with code 1
Administrator access is required to install Claude with full features.
Expected Behavior: Cowork installs alongside Claude when running with administrator privileges.
Actual Behavior: Cowork is absent after every install attempt despite full elevation.

What Should Happen?

When the Claude desktop installer is run with full administrator privileges, Cowork should install successfully alongside Claude and be accessible within the app. The AddPackage step should complete without error and Cowork should appear as a feature in the Claude desktop application.

Error Messages/Logs

2026/04/16 11:48:27.215961 MSIX installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF6
2026/04/16 11:48:27.215961 ERROR dialog (opening log): Installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF6
2026/04/16 11:49:09.091077 Elevated process exited with code 1
2026/04/16 11:49:09.091077 Elevation failed: elevated installer exited with code 1
2026/04/16 11:49:09.091077 ERROR dialog (with log path): Administrator access is required to install Claude with full features. You can try again or install without Cowork.

2026/04/16 11:51:16.585621 MSIX installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF6
2026/04/16 11:51:16.585621 ERROR dialog (opening log): Installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF6
2026/04/16 11:51:49.816248 Elevated process exited with code 1
2026/04/16 11:51:49.816248 Elevation failed: elevated installer exited with code 1
2026/04/16 11:51:49.816248 ERROR dialog (with log path): Administrator access is required to install Claude with full features. You can try again or install without Cowork.

2026/04/16 11:52:54.221539 MSIX installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF6
2026/04/16 11:52:54.221539 ERROR dialog (opening log): Installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF6
2026/04/16 11:52:56.867109 Elevated process exited with code 1
2026/04/16 11:52:56.867109 Elevation failed: elevated installer exited with code 1
2026/04/16 11:52:56.867109 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:

Download the Claude desktop installer from claude.ai/download
Right-click the installer (Claude Setup.exe) and select Run as administrator
Accept the UAC prompt when prompted
Observe that Claude installs and launches successfully
Open the Claude desktop app
Note that Cowork is absent — it does not appear anywhere in the app
To confirm the failure, check the install log at:
C:\Users\[username]\AppData\Local\Temp\ClaudeSetup.log
Repeat steps 1–7 — the same result occurs consistently across multiple attempts

Additional context: The installer self-elevates to full admin (Elevation type: Full, Is elevated: true confirmed in logs), downloads and verifies the MSIX successfully, but fails specifically at the AddPackage (current-user) step for the Cowork component every time.

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

Version: Claude Desktop App – latest (installed April 16, 2026)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Here's your Additional Information section:

Additional Information:
Misdirected Support Response:
Anthropic support responded to this issue and directed me to submit this bug report at https://github.com/anthropics/claude-code/issues, which is the repository for the Claude Code CLI tool — not the Claude desktop app. This suggests there may be an internal routing or documentation issue on Anthropic's end regarding where desktop app bugs should be reported. I am submitting here as the most appropriate alternative.
Support Response Received:
Anthropic support confirmed the following:

HRESULT 0x80073CF6 is a Windows AppX install failure
Cowork requires administrator privileges to install
Despite running with full administrator privileges (confirmed via logs), Cowork still fails to install
Support acknowledged this as a Windows install bug worth investigating

Key Log Findings:

Installer confirms full elevation: Elevation type: Full / Is elevated: true
Sideloading is enabled: Sideloading enabled: true
Claude MSIX installs successfully every time — failure is isolated specifically to the Cowork component
Error occurs consistently across 3+ separate install attempts on the same machine
A 4th install attempt succeeded for Claude but silently skipped Cowork entirely

System Details:

Windows 11 Professional, build 10.0.26200, x64
Not in S Mode
No conflicting services detected by installer
User account has elevation capability confirmed by installer logs

Full install log attached: ClaudeSetup.log

ClaudeSetup.log