Fixing Claude Desktop Install Errors on Windows (0x80073CF6 / 0x80073D05)

Symptom

The Claude Desktop installer (ClaudeSetup.exe) fails with:

Installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF6

Opening the setup log — the error dialog offers to — may reveal a more specific underlying error:

0x80073D05: An error occurred while deleting the package's previously existing
application data. ... failed to register the windows.stateExtension extension
in the registry.

Root cause

Windows keeps a per-app data folder for every MSIX package:

%LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc

When reinstalling, the installer tries to wipe this folder before writing fresh data. If any process still holds an open file handle inside it, Windows cannot delete it and the install fails with the errors above — even though Get-AppxPackage *Claude* shows no installed package at all. That is exactly what makes this error confusing: there is nothing to "uninstall", yet the install keeps failing.

In the case this guide is based on, the leftover handles belonged to:

• chrome-native-host.exe — part of the "Claude for Chrome" native messaging host
• cmd.exe

Both were holding files open under ...\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\ChromeNativeHost.

The fix

1. Confirm there is no stuck package (optional, for context)

In PowerShell (no admin needed):

Get-AppxPackage *Claude*
Get-ChildItem "C:\Program Files\WindowsApps" -Force | Where-Object {$_.Name -like "*Claude*"}

If both return nothing, the problem is not a stuck package — it is a locked data folder.

2. Find what is locking the folder

1. Press Win + R and run resmon (Resource Monitor).
2. Open the CPU tab.
3. Scroll down to Associated Handles.
4. In the search box, type Claude_pzs8sxrjxfjjc.
5. Note every process listed — commonly chrome-native-host.exe and/or cmd.exe, sometimes explorer.exe if the folder is open in a File Explorer window.

3. Kill the blocking processes

Right-click each process found in step 2, then End Process.

If chrome-native-host.exe keeps reappearing, close every Chrome window and make sure no chrome.exe remains in Task Manager — Chrome respawns this helper process automatically.

4. Delete the leftover data folder

Search Claude_pzs8sxrjxfjjc again in Resource Monitor to confirm no handles remain, then delete the folder in File Explorer: %LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc.

If the manual delete is refused, take ownership first (admin PowerShell):

takeown /f "$env:LOCALAPPDATA\Packages\Claude_pzs8sxrjxfjjc" /r /d y
icacls "$env:LOCALAPPDATA\Packages\Claude_pzs8sxrjxfjjc" /grant "${env:USERNAME}:F" /t
Remove-Item "$env:LOCALAPPDATA\Packages\Claude_pzs8sxrjxfjjc" -Recurse -Force

5. Reinstall

Re-run ClaudeSetup.exe. It should now complete successfully.

Quick checklist

1. Get-AppxPackage *Claude* returns nothing → not a stuck-package issue.
2. resmon → CPU tab → Associated Handles → search Claude_pzs8sxrjxfjjc.
3. End any process holding handles (especially chrome-native-host.exe and cmd.exe).
4. Delete %LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc.
5. Reinstall Claude Desktop.

If this doesn't apply, check these first

• Antivirus interference — Kaspersky and similar suites can silently block MSIX AddPackage calls. Temporarily disable real-time protection and retry.
• Corrupted system files — sfc /scannow then DISM /Online /Cleanup-Image /RestoreHealth (admin PowerShell) rule out Windows component corruption.
• AppX services — confirm AppXSvc and ClipSVC are running: Get-Service AppXSvc, ClipSVC.
• Detailed error logs — Event Viewer → Applications and Services Logs → Microsoft → Windows → AppXDeploymentServer → Operational gives a far more precise error than the HRESULT alone.