[Bug] MSIX installation failed with error code 0x80073CF6 on Windows 11

**Bug Description**
2026/08/22 09:19:43.822907 Log file: C:\Users\JDM-SE~1\AppData\Local\Temp\ClaudeSetup.log
2026/08/22 09:19:43.838915 === Claude Setup 255293a41a25d54c5177aa9614fb4cd620e70b78 started ===
2026/08/22 09:19:43.838915 AllowDevelopmentWithoutDevLicense found with value: 1
2026/08/22 09:19:43.838915 Windows edition: ProfessionalWorkstation
2026/08/22 09:19:43.839432 Windows version: 10.0.22631
2026/08/22 09:19:43.839432 Native arch: x64
2026/08/22 09:19:43.839432 Elevation type: Limited
2026/08/22 09:19:43.839432 Is elevated: false
2026/08/22 09:19:43.839432 Sideloading enabled: true
2026/08/22 09:19:43.839432 S Mode: false
2026/08/22 09:19:43.839949 Conflicting service: false
2026/08/22 09:19:43.839949 Running in non-elevated context
2026/08/22 09:19:43.839949 User can elevate — installing MSIX directly
2026/08/22 09:19:43.853227 Splash: 400x300, 8 frame(s), animated=true
2026/08/22 09:19:43.853743 System DPI: 96 (scale: 100%)
2026/08/22 09:19:43.882435 MSIX URL: https://api.anthropic.com/api/desktop/win32/x64/msix/latest/redirect
2026/08/22 09:19:43.883473 Downloading MSIX to C:\Users\JDM-SE~1\AppData\Local\Temp\Claude-3748625599.msix
2026/08/22 09:19:43.891247 proxy: WinHttpGetProxyForUrl("https://api.anthropic.com/api/desktop/win32/x64/msix/latest/redirect"): winapi error #12180
2026/08/22 09:19:44.173747 proxy: WinHttpGetProxyForUrl("https://downloads.claude.ai/releases/win32/x64/1.34493.1/Claude-255293a41a25d54c5177aa9614fb4cd620e70b78.msix"): winapi error #12180
2026/08/22 09:19:44.454325 Download progress: 10% (24772432 / 247405438 bytes)
2026/08/22 09:19:44.673899 Download progress: 20% (49512080 / 247405438 bytes)
2026/08/22 09:19:44.896295 Download progress: 30% (74235344 / 247405438 bytes)
2026/08/22 09:19:45.109383 Download progress: 40% (98974992 / 247405438 bytes)
2026/08/22 09:19:45.325535 Download progress: 50% (123731024 / 247405438 bytes)
2026/08/22 09:19:45.548596 Download progress: 60% (148454304 / 247405438 bytes)
2026/08/22 09:19:45.768543 Download progress: 70% (173193952 / 247405438 bytes)
2026/08/22 09:19:46.000119 Download progress: 80% (197933600 / 247405438 bytes)
2026/08/22 09:19:46.215769 Download progress: 90% (222673248 / 247405438 bytes)
2026/08/22 09:19:46.439617 Download progress: 100% (247405438 / 247405438 bytes)
2026/08/22 09:19:46.441748 Download complete: 247405438 bytes, SHA256: ad5ead595fec1977c0ccb1d7fab3be040773b716451431dbd6bab457ba31a55c
2026/08/22 09:19:46.442766 Download complete
2026/08/22 09:19:46.452558 Self-elevating: E:\Downloads\Claude Setup (3).exe --elevated --msix-path "C:\Users\JDM-SE~1\AppData\Local\Temp\Claude-3748625599.msix" --log-path "C:\Users\JDM-SE~1\AppData\Local\Temp\ClaudeSetup.log"
2026/08/22 09:19:48.606476 Waiting for elevated process to complete...
2026/08/22 09:19:48.619482 Log file: C:\Users\JDM-SE~1\AppData\Local\Temp\ClaudeSetup.log
2026/08/22 09:19:48.633957 === Claude Setup 255293a41a25d54c5177aa9614fb4cd620e70b78 started ===
2026/08/22 09:19:48.633957 AllowDevelopmentWithoutDevLicense found with value: 1
2026/08/22 09:19:48.633957 Windows edition: ProfessionalWorkstation
2026/08/22 09:19:48.634471 Windows version: 10.0.22631
2026/08/22 09:19:48.634471 Native arch: x64
2026/08/22 09:19:48.634471 Elevation type: Full
2026/08/22 09:19:48.634471 Is elevated: true
2026/08/22 09:19:48.634471 Sideloading enabled: true
2026/08/22 09:19:48.634471 S Mode: false
2026/08/22 09:19:48.634471 Conflicting service: false
2026/08/22 09:19:48.634471 Running in elevated context
2026/08/22 09:19:48.634471 Installing MSIX from C:\Users\JDM-SE~1\AppData\Local\Temp\Claude-3748625599.msix (all-users: false)
2026/08/22 09:19:48.647549 Splash: 400x300, 8 frame(s), animated=true
2026/08/22 09:19:48.647549 System DPI: 96 (scale: 100%)
2026/08/22 09:19:48.675058 Verifying Authenticode signature on C:\Users\JDM-SE~1\AppData\Local\Temp\Claude-3748625599.msix
2026/08/22 09:19:49.474253 WinVerifyTrust: MSIX signature is valid
2026/08/22 09:19:49.902963 Signature verified: MSIX signer matches bootstrapper
2026/08/22 09:19:49.904529 Extracted family name from MSIX manifest: Claude_pzs8sxrjxfjjc
2026/08/22 09:19:49.904529 Squirrel process prefix: c:\users\jdm-server\appdata\local\anthropicclaude\
2026/08/22 09:19:49.904529 Checking for running Squirrel Claude processes...
2026/08/22 09:19:49.912295 No Squirrel Claude processes found
2026/08/22 09:19:49.912295 Checking for existing Claude MSIX packages...
2026/08/22 09:19:49.926293 Installing MSIX: C:\Users\JDM-SE~1\AppData\Local\Temp\Claude-3748625599.msix
2026/08/22 09:19:49.926293 Standard install (not split-account), using AddPackage
2026/08/22 09:19:49.926293 Installing via AddPackage (current-user)...
2026/08/22 09:20:13.195197 MSIX installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF6
2026/08/22 09:20:13.195197 ERROR dialog (opening log): Installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF6

Please share this log with us.
2026/08/22 09:20:30.122221 Elevated process exited with code 1
2026/08/22 09:20:30.122221 Elevation failed: elevated installer exited with code 1
20…
**Note:** Content was truncated.

Start with the attached ClaudeSetup.log and the installer path that invokes AddPackage; investigate the conditions producing HRESULT 0x80073CF6 on Windows 11. Done means reproducing the failed MSIX installation and resolving the installer behavior so the package installs successfully.

Written by the indexing model from the issue text.