### Preflight Checklist - [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) 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? Impossible to install Claude code. Setup fails on my computer OS = Windows 11 professional / Windows version: 10.0.26100 / french language Claude Setup do

[BUG] Claude Desktop installation fails - Administrator access required (Cowork) on Windows 11 Pro Build 26100

Status Open

Maintainer reply None cached

Activity 0 comments · opened Aug 28, 2026

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?

Impossible to install Claude code. Setup fails on my computer
OS = Windows 11 professional / Windows version: 10.0.26100 / french language
Claude Setup downloaded from official website this 26th august 2026

i've tried to run as administrator and process fails with two error dialog :
_Installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF9_
then
_Administrator access is required to install Claude with full features. You can try again or install without Cowork._

But i'm administrator when running so last message is probably not the issue.

Seems like a bug, similar issues like these two :
https://github.com/anthropics/claude-code/issues/76510
https://github.com/anthropics/claude-code/issues/77861

What Should Happen?

Setup should reach the end with no error.

Error Messages/Logs

2026/08/28 19:01:11.175693 Elevated process exited with code 1
2026/08/28 19:01:11.176206 Elevation failed: elevated installer exited with code 1
2026/08/28 19:01:11.176206 ERROR dialog (with log path): Administrator access is required to install Claude with full features. You can try again or install without Cowork.
2026/08/28 19:01:47.418730 Log file: C:\Users\***\AppData\Local\Temp\ClaudeSetup.log
2026/08/28 19:01:47.449187 === Claude Setup 28dcf5a3323c61fa946efcc50e7112a198ea503c started ===
2026/08/28 19:01:47.449187 Windows edition: Professional
2026/08/28 19:01:47.450340 Windows version: 10.0.26100
2026/08/28 19:01:47.450340 Native arch: x64
2026/08/28 19:01:47.450847 Elevation type: Full
2026/08/28 19:01:47.450847 Is elevated: true
2026/08/28 19:01:47.450847 Sideloading enabled: true
2026/08/28 19:01:47.450847 S Mode: false
2026/08/28 19:01:47.450847 Conflicting service: false
2026/08/28 19:01:47.450847 Running in non-elevated context
2026/08/28 19:01:47.450847 User can elevate — installing MSIX directly
2026/08/28 19:01:47.478297 Splash: 400x300, 8 frame(s), animated=true
2026/08/28 19:01:47.478297 System DPI: 144 (scale: 150%)
2026/08/28 19:01:47.524680 MSIX URL: https://api.anthropic.com/api/desktop/win32/x64/msix/latest/redirect
2026/08/28 19:01:47.525815 Downloading MSIX to C:\Users\***\AppData\Local\Temp\Claude-3213046610.msix
2026/08/28 19:01:47.538106 proxy: WinHttpGetProxyForUrl("https://api.anthropic.com/api/desktop/win32/x64/msix/latest/redirect"): winapi error #12180
2026/08/28 19:01:48.354695 proxy: WinHttpGetProxyForUrl("https://downloads.claude.ai/releases/win32/x64/1.37937.3/Claude-28dcf5a3323c61fa946efcc50e7112a198ea503c.msix"): winapi error #12180
2026/08/28 19:01:55.891497 Download progress: 10% (26116096 / 261041041 bytes)
2026/08/28 19:02:04.522142 Download progress: 20% (52215808 / 261041041 bytes)
2026/08/28 19:02:13.009636 Download progress: 30% (78331632 / 261041041 bytes)
2026/08/28 19:02:24.808437 Download progress: 40% (104447984 / 261041041 bytes)
2026/08/28 19:02:38.664612 Download progress: 50% (130530880 / 261041041 bytes)
2026/08/28 19:02:51.771998 Download progress: 60% (156630912 / 261041041 bytes)
2026/08/28 19:03:03.248417 Download progress: 70% (182745968 / 261041041 bytes)
2026/08/28 19:03:16.126442 Download progress: 80% (208846576 / 261041041 bytes)
2026/08/28 19:03:26.329213 Download progress: 90% (234961184 / 261041041 bytes)
2026/08/28 19:03:37.763421 Download progress: 100% (261041041 / 261041041 bytes)
2026/08/28 19:03:37.766068 Download complete: 261041041 bytes, SHA256: d503121b01237cfdc26b74c86fc3acbd2513877d127b5516968a8c78921aa66b
2026/08/28 19:03:37.766600 Download complete
2026/08/28 19:03:37.775712 Self-elevating: C:\DL\DL\Claude Setup.exe --elevated --msix-path "C:\Users\***\AppData\Local\Temp\Claude-3213046610.msix" --log-path "C:\Users\***\AppData\Local\Temp\ClaudeSetup.log"
2026/08/28 19:03:37.851194 Waiting for elevated process to complete...
2026/08/28 19:03:37.860538 Log file: C:\Users\***\AppData\Local\Temp\ClaudeSetup.log
2026/08/28 19:03:37.886935 === Claude Setup 28dcf5a3323c61fa946efcc50e7112a198ea503c started ===
2026/08/28 19:03:37.886935 Windows edition: Professional
2026/08/28 19:03:37.887459 Windows version: 10.0.26100
2026/08/28 19:03:37.887459 Native arch: x64
2026/08/28 19:03:37.887459 Elevation type: Full
2026/08/28 19:03:37.887459 Is elevated: true
2026/08/28 19:03:37.887459 Sideloading enabled: true
2026/08/28 19:03:37.887459 S Mode: false
2026/08/28 19:03:37.887459 Conflicting service: false
2026/08/28 19:03:37.887459 Running in elevated context
2026/08/28 19:03:37.888017 Installing MSIX from C:\Users\***\AppData\Local\Temp\Claude-3213046610.msix (all-users: false)
2026/08/28 19:03:37.916734 Splash: 400x300, 8 frame(s), animated=true
2026/08/28 19:03:37.916734 System DPI: 144 (scale: 150%)
2026/08/28 19:03:37.957882 Verifying Authenticode signature on C:\Users\***\AppData\Local\Temp\Claude-3213046610.msix
2026/08/28 19:03:39.507327 WinVerifyTrust: MSIX signature is valid
2026/08/28 19:03:40.289713 Signature verified: MSIX signer matches bootstrapper
2026/08/28 19:03:40.293216 Extracted family name from MSIX manifest: Claude_pzs8sxrjxfjjc
2026/08/28 19:03:40.293216 Squirrel process prefix: C:\Users\***\appdata\local\anthropicclaude\
2026/08/28 19:03:40.293216 Checking for running Squirrel Claude processes...
2026/08/28 19:03:40.297830 No Squirrel Claude processes found
2026/08/28 19:03:40.297830 Checking for existing Claude MSIX packages...
2026/08/28 19:03:40.313095 Installing MSIX: C:\Users\***\AppData\Local\Temp\Claude-3213046610.msix
2026/08/28 19:03:40.313095 Standard install (not split-account), using AddPackage
2026/08/28 19:03:40.313095 Installing via AddPackage (current-user)...
2026/08/28 19:03:41.579376 MSIX installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF9
2026/08/28 19:03:41.579376 ERROR dialog (opening log): Installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF9

Please share this log with us.
2026/08/28 19:03:55.281545 Elevated process exited with code 1
2026/08/28 19:03:55.281545 Elevation failed: elevated installer exited with code 1
2026/08/28 19:03:55.281545 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

run setup as administratot
wait
error 1 occurs (dialog #1) : Installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF9
error 2 occurs (dialog #2) : Administrator access is required to install Claude with full features. You can try again or install without Cowork.

installation failed

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

N/A

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

View original on GitHub ↗