[BUG] Cowork tab missing after overnight auto-update (7/7→7/8) — Windows 11 Home, previously working 30+ days- AddPackage failed: 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?

Cowork tab in Claude Desktop App working for 30 + days, broke overnight on 7/7→7/8 with build 1.19367.0, same hardware.

AddPackage failed: HRESULT 0x80073CF6

Now the tab doesn't show anymore. I uninstalled and attempted to reinstall the latest Claude Desktop App on the same windows PC and now I get errors. Windows 11 Home, same machine throughout

ClaudeSetup.log

What Should Happen?

I should have the Claude Cowork tab in my Claude desktop App, I should be able to reinstall Claude Desktop App without errors. Windows 11 Home, same machine throughout

Error Messages/Logs

AddPackage failed: HRESULT 0x80073CF6

Steps to Reproduce

Had Claude Desktop installed and Cowork tab fully functional on Windows 11 Home for 30+ days
App auto-updated overnight between 7/7/2026 and 7/8/2026
Launched Claude Desktop on 7/8 — Cowork tab completely absent, only Chat and Code visible
Attempted reinstall: uninstalled via Windows Settings → Apps
Removed MSIX package manually via PowerShell (Get-AppxPackage -Name "Claude" | Remove-AppxPackage)
Re-ran Claude Setup.exe as Administrator
Installer fails at ~50% with AddPackage failed: HRESULT 0x80073CF6
Error message states "Administrator access is required to install Claude with full features" despite running as Administrator on an admin account

Expected Behavior: Cowork tab present and functional as it was for the previous 30+ days on this identical hardware and OS
Actual Behavior: Cowork tab missing; reinstall fails with HRESULT 0x80073CF6; installer log flags Windows edition: Core as apparent blocker despite Cowork working on this same machine previously
Environment:

OS: Windows 11 Home (Core), version 10.0.26200, x64
Last known working: 7/7/2026
Broke: overnight auto-update 7/7→7/8
Build: 1.19367.0 (Claude-1a5be1fbf83d1832486e03a667557c18f0a0ec7a)

Attach: C:\Users\chris\AppData\Local\Temp\ClaudeSetup.log

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

1.19367.0 (full build hash: 1a5be1fbf83d1832486e03a667557c18f0a0ec7a).

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_