### 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? Title: MSIX AddPackage fails with HRESULT 0x80073CFF on clean Windows 11 Pro 26200 — confirmed not caused by leftover state Body: Reproducible on Windows

MSIX AddPackage fails with HRESULT 0x80073CFF on clean Windows 11 Pro 26200 — confirmed not caused by leftover state Body:

Resolved 💬 2 comments Opened Jul 1, 2026 by Sander-Hazewinkel Closed Jul 5, 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?

Title: MSIX AddPackage fails with HRESULT 0x80073CFF on clean Windows 11 Pro 26200 — confirmed not caused by leftover state
Body:
Reproducible on Windows 11 Pro, build 10.0.26200. Installer log attached (ClaudeSetup.log).
Previously working install (v1.6608.2.0) stopped functioning; subsequent update/reinstall attempts consistently fail at AddPackage with HRESULT 0x80073CFF. MSIX signature verifies successfully every time.
I did a full manual audit and cleanup of every location Windows tracks for this package, to rule out leftover state as the cause:

Get-AppxPackage -AllUsers — returned nothing (package invisible to normal enumeration)
C:\Program Files\WindowsApps\Claude_1.6608.2.0_x64__pzs8sxrjxfjjc — orphaned folder found, present on disk despite not showing in Get-AppxPackage. Removed successfully via Remove-AppxPackage -Package "Claude_1.6608.2.0_x64__pzs8sxrjxfjjc" -AllUsers
icacls on that folder — confirmed standard/correct permissions (TrustedInstaller owner, normal AppX package ACLs). Not a permissions issue.
%LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc — per-user app data/registry hive found, last-written at install-attempt time. A locked file (chrome-native-host.exe, held by a still-running orphaned process from the old install) initially blocked removal; killed the process, then removed the folder successfully.
%LOCALAPPDATA%\AnthropicClaude (old Squirrel installer path) — empty
SystemAppData registry key — no entry
Get-StartApps — no ghost Start Menu tile for the app itself

After this full cleanup, with zero Claude-related registrations, files, or processes remaining anywhere on the system, a fresh install attempt still fails identically: AddPackage rejects the package in <0.3s, with no removal step even attempted (nothing left to remove). Same HRESULT every time.
This rules out leftover/orphaned local state as the cause. Related: #64029, #60319, #58174, #49917 — all same build, same error, same pattern of exhausted local workarounds.

That's the report. File it, attach the log, and I'd flag Cowork specifically as the blocking dependency for you in the issue body — that's the detail that should get it prioritized rather than filed as a duplicate and left alone.

2026/07/01 12:46:30.029532 Log file: C:\Users\sande\AppData\Local\Temp\ClaudeSetup.log
2026/07/01 12:46:30.030162 === Claude Setup 2b3ab429b13f2c904d7552b7ca82a0d2a22af52f started ===
2026/07/01 12:46:30.030721 Windows edition: Professional
2026/07/01 12:46:30.031280 WARNING: CoworkVMService already exists (potential conflict)
2026/07/01 12:46:30.031280 Windows version: 10.0.26200
2026/07/01 12:46:30.031280 Native arch: x64
2026/07/01 12:46:30.031280 Elevation type: Limited
2026/07/01 12:46:30.031280 Is elevated: false
2026/07/01 12:46:30.031280 Sideloading enabled: true
2026/07/01 12:46:30.031280 S Mode: false
2026/07/01 12:46:30.031280 Conflicting service: true
2026/07/01 12:46:30.031280 Running in non-elevated context
2026/07/01 12:46:30.031901 User can elevate — installing MSIX directly
2026/07/01 12:46:30.046828 Splash: 400x300, 8 frame(s), animated=true
2026/07/01 12:46:30.046828 System DPI: 144 (scale: 150%)
2026/07/01 12:46:30.074335 MSIX URL: https://api.anthropic.com/api/desktop/win32/x64/msix/latest/redirect
2026/07/01 12:46:30.074848 Downloading MSIX to C:\Users\sande\AppData\Local\Temp\Claude-2186183292.msix
2026/07/01 12:46:30.082130 proxy: WinHttpGetProxyForUrl("https://api.anthropic.com/api/desktop/win32/x64/msix/latest/redirect"): winapi error #12180
2026/07/01 12:46:30.255443 proxy: WinHttpGetProxyForUrl("https://downloads.claude.ai/releases/win32/x64/1.17377.1/Claude-2b3ab429b13f2c904d7552b7ca82a0d2a22af52f.msix"): winapi error #12180
2026/07/01 12:46:34.301990 Download progress: 10% (23428944 / 234211264 bytes)
2026/07/01 12:46:38.590615 Download progress: 20% (46857888 / 234211264 bytes)
2026/07/01 12:46:43.665959 Download progress: 30% (70269872 / 234211264 bytes)
2026/07/01 12:46:48.150200 Download progress: 40% (93698816 / 234211264 bytes)
2026/07/01 12:46:52.577543 Download progress: 50% (117111376 / 234211264 bytes)
2026/07/01 12:46:56.779433 Download progress: 60% (140540880 / 234211264 bytes)
2026/07/01 12:47:00.634385 Download progress: 70% (163953440 / 234211264 bytes)
2026/07/01 12:47:04.434270 Download progress: 80% (187382384 / 234211264 bytes)
2026/07/01 12:47:08.270240 Download progress: 90% (210810752 / 234211264 bytes)
2026/07/01 12:47:12.548486 Download progress: 100% (234211264 / 234211264 bytes)
2026/07/01 12:47:12.549508 Download complete: 234211264 bytes, SHA256: 553b9161d1913ed38dd2990d3d0ed9ce9cfbda2a2167dc17b9966e7ea809fb16
2026/07/01 12:47:12.549508 Download complete
2026/07/01 12:47:12.573534 Self-elevating: D:\Claude Setup (2).exe --elevated --msix-path "C:\Users\sande\AppData\Local\Temp\Claude-2186183292.msix" --log-path "C:\Users\sande\AppData\Local\Temp\ClaudeSetup.log"
2026/07/01 12:47:16.894915 Waiting for elevated process to complete...
2026/07/01 12:47:16.902427 Log file: C:\Users\sande\AppData\Local\Temp\ClaudeSetup.log
2026/07/01 12:47:16.902427 === Claude Setup 2b3ab429b13f2c904d7552b7ca82a0d2a22af52f started ===
2026/07/01 12:47:16.903551 Windows edition: Professional
2026/07/01 12:47:16.903551 WARNING: CoworkVMService already exists (potential conflict)
2026/07/01 12:47:16.903551 Windows version: 10.0.26200
2026/07/01 12:47:16.903551 Native arch: x64
2026/07/01 12:47:16.903551 Elevation type: Full
2026/07/01 12:47:16.903551 Is elevated: true
2026/07/01 12:47:16.903551 Sideloading enabled: true
2026/07/01 12:47:16.903551 S Mode: false
2026/07/01 12:47:16.903551 Conflicting service: true
2026/07/01 12:47:16.904086 Running in elevated context
2026/07/01 12:47:16.904086 Installing MSIX from C:\Users\sande\AppData\Local\Temp\Claude-2186183292.msix (all-users: false)
2026/07/01 12:47:16.920368 Splash: 400x300, 8 frame(s), animated=true
2026/07/01 12:47:16.920880 System DPI: 144 (scale: 150%)
2026/07/01 12:47:16.942107 Verifying Authenticode signature on C:\Users\sande\AppData\Local\Temp\Claude-2186183292.msix
2026/07/01 12:47:17.443678 WinVerifyTrust: MSIX signature is valid
2026/07/01 12:47:17.657506 Signature verified: MSIX signer matches bootstrapper
2026/07/01 12:47:17.658019 Extracted family name from MSIX manifest: Claude_pzs8sxrjxfjjc
2026/07/01 12:47:17.658019 Squirrel process prefix: c:\users\sande\appdata\local\anthropicclaude\
2026/07/01 12:47:17.658019 Checking for running Squirrel Claude processes...
2026/07/01 12:47:17.663421 No Squirrel Claude processes found
2026/07/01 12:47:17.663421 Removing conflicting CoworkVMService...
2026/07/01 12:47:17.663421 WARNING: failed to remove conflicting service: could not open CoworkVMService: Access is denied.
2026/07/01 12:47:17.663421 Checking for existing Claude MSIX packages...
2026/07/01 12:47:17.674822 Removing: Claude_1.6608.2.0_x64__pzs8sxrjxfjjc
2026/07/01 12:47:17.693957 WARNING: Remove failed for Claude_1.6608.2.0_x64__pzs8sxrjxfjjc: RemovePackage failed with HRESULT 0x80073CFA
2026/07/01 12:47:17.702506 Removing (user): Claude_1.6608.2.0_x64__pzs8sxrjxfjjc
2026/07/01 12:47:17.704607 WARNING: Remove failed for Claude_1.6608.2.0_x64__pzs8sxrjxfjjc: RemovePackage failed with HRESULT 0x80073CFA
2026/07/01 12:47:17.704607 Installing MSIX: C:\Users\sande\AppData\Local\Temp\Claude-2186183292.msix
2026/07/01 12:47:17.704607 Standard install (not split-account), using AddPackage
2026/07/01 12:47:17.704607 Installing via AddPackage (current-user)...
2026/07/01 12:47:17.963721 MSIX installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CFF
2026/07/01 12:47:17.963721 ERROR dialog (opening log): Installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CFF

Please share this log with us.
2026/07/01 12:57:10.713909 Elevated process exited with code 1
2026/07/01 12:57:10.713909 Elevation failed: elevated installer exited with code 1
2026/07/01 12:57:10.713909 ERROR dialog (with log path): Administrator access is required to install Claude with full features. You can try again or install without Cowork.
2026/07/01 12:57:31.319258 Log file: C:\Users\sande\AppData\Local\Temp\ClaudeSetup.log
2026/07/01 12:57:31.319771 === Claude Setup 2b3ab429b13f2c904d7552b7ca82a0d2a22af52f started ===
2026/07/01 12:57:31.320285 AllowDevelopmentWithoutDevLicense found with value: 1
2026/07/01 12:57:31.320285 Windows edition: Professional
2026/07/01 12:57:31.320285 WARNING: CoworkVMService already exists (potential conflict)
2026/07/01 12:57:31.320285 Windows version: 10.0.26200
2026/07/01 12:57:31.320285 Native arch: x64
2026/07/01 12:57:31.320285 Elevation type: Limited
2026/07/01 12:57:31.320285 Is elevated: false
2026/07/01 12:57:31.320285 Sideloading enabled: true
2026/07/01 12:57:31.320285 S Mode: false
2026/07/01 12:57:31.320285 Conflicting service: true
2026/07/01 12:57:31.320285 Running in non-elevated context
2026/07/01 12:57:31.320285 User can elevate — installing MSIX directly
2026/07/01 12:57:31.335502 Splash: 400x300, 8 frame(s), animated=true
2026/07/01 12:57:31.335502 System DPI: 144 (scale: 150%)
2026/07/01 12:57:31.359542 MSIX URL: https://api.anthropic.com/api/desktop/win32/x64/msix/latest/redirect
2026/07/01 12:57:31.360066 Downloading MSIX to C:\Users\sande\AppData\Local\Temp\Claude-845941621.msix
2026/07/01 12:57:31.366537 proxy: WinHttpGetProxyForUrl("https://api.anthropic.com/api/desktop/win32/x64/msix/latest/redirect"): winapi error #12180
2026/07/01 12:57:31.566873 proxy: WinHttpGetProxyForUrl("https://downloads.claude.ai/releases/win32/x64/1.17377.1/Claude-2b3ab429b13f2c904d7552b7ca82a0d2a22af52f.msix"): winapi error #12180
2026/07/01 12:57:36.857615 Download progress: 10% (23428944 / 234211264 bytes)
2026/07/01 12:57:41.722645 Download progress: 20% (46857888 / 234211264 bytes)
2026/07/01 12:57:46.391865 Download progress: 30% (70269872 / 234211264 bytes)
2026/07/01 12:57:59.358424 Download progress: 40% (93698816 / 234211264 bytes)
2026/07/01 12:58:04.488224 Download progress: 50% (117111376 / 234211264 bytes)
2026/07/01 12:58:09.140917 Download progress: 60% (140540880 / 234211264 bytes)
2026/07/01 12:58:13.766503 Download progress: 70% (163953440 / 234211264 bytes)
2026/07/01 12:58:18.625208 Download progress: 80% (187398768 / 234211264 bytes)
2026/07/01 12:58:23.146797 Download progress: 90% (210810752 / 234211264 bytes)
2026/07/01 12:58:27.795697 Download progress: 100% (234211264 / 234211264 bytes)
2026/07/01 12:58:27.797015 Download complete: 234211264 bytes, SHA256: 553b9161d1913ed38dd2990d3d0ed9ce9cfbda2a2167dc17b9966e7ea809fb16
2026/07/01 12:58:27.797015 Download complete
2026/07/01 12:58:27.803812 Self-elevating: D:\Claude Setup (2).exe --elevated --msix-path "C:\Users\sande\AppData\Local\Temp\Claude-845941621.msix" --log-path "C:\Users\sande\AppData\Local\Temp\ClaudeSetup.log"
2026/07/01 13:00:30.015272 Elevation failed: ShellExecuteEx failed: The operation was canceled by the user.
2026/07/01 13:00:30.015272 ERROR dialog (with log path): Administrator access is required to install Claude with full features. You can try again or install without Cowork.
2026/07/01 14:16:52.111486 Log file: C:\Users\sande\AppData\Local\Temp\ClaudeSetup.log
2026/07/01 14:16:52.111486 === Claude Setup 2b3ab429b13f2c904d7552b7ca82a0d2a22af52f started ===
2026/07/01 14:16:52.111992 AllowDevelopmentWithoutDevLicense found with value: 1
2026/07/01 14:16:52.111992 Windows edition: Professional
2026/07/01 14:16:52.112504 Windows version: 10.0.26200
2026/07/01 14:16:52.112504 Native arch: x64
2026/07/01 14:16:52.112504 Elevation type: Limited
2026/07/01 14:16:52.112504 Is elevated: false
2026/07/01 14:16:52.112504 Sideloading enabled: true
2026/07/01 14:16:52.112504 S Mode: false
2026/07/01 14:16:52.112504 Conflicting service: false
2026/07/01 14:16:52.112504 Running in non-elevated context
2026/07/01 14:16:52.112504 User can elevate — installing MSIX directly
2026/07/01 14:16:52.126371 Splash: 400x300, 8 frame(s), animated=true
2026/07/01 14:16:52.126371 System DPI: 144 (scale: 150%)
2026/07/01 14:16:52.152297 MSIX URL: https://api.anthropic.com/api/desktop/win32/x64/msix/latest/redirect
2026/07/01 14:16:52.152829 Downloading MSIX to C:\Users\sande\AppData\Local\Temp\Claude-2062474194.msix
2026/07/01 14:16:52.159669 proxy: WinHttpGetProxyForUrl("https://api.anthropic.com/api/desktop/win32/x64/msix/latest/redirect"): winapi error #12180
2026/07/01 14:16:52.369361 proxy: WinHttpGetProxyForUrl("https://downloads.claude.ai/releases/win32/x64/1.17377.1/Claude-2b3ab429b13f2c904d7552b7ca82a0d2a22af52f.msix"): winapi error #12180
2026/07/01 14:16:55.718366 Download progress: 10% (23428944 / 234211264 bytes)
2026/07/01 14:16:59.061266 Download progress: 20% (46857888 / 234211264 bytes)
2026/07/01 14:17:03.104439 Download progress: 30% (70286256 / 234211264 bytes)
2026/07/01 14:17:06.222592 Download progress: 40% (93698816 / 234211264 bytes)
2026/07/01 14:17:09.289275 Download progress: 50% (117111376 / 234211264 bytes)
2026/07/01 14:17:12.488625 Download progress: 60% (140540880 / 234211264 bytes)
2026/07/01 14:17:15.484569 Download progress: 70% (163953440 / 234211264 bytes)
2026/07/01 14:17:18.600375 Download progress: 80% (187382384 / 234211264 bytes)
2026/07/01 14:17:21.517694 Download progress: 90% (210794368 / 234211264 bytes)
2026/07/01 14:17:24.342425 Download progress: 100% (234211264 / 234211264 bytes)
2026/07/01 14:17:24.343129 Download complete: 234211264 bytes, SHA256: 553b9161d1913ed38dd2990d3d0ed9ce9cfbda2a2167dc17b9966e7ea809fb16
2026/07/01 14:17:24.343722 Download complete
2026/07/01 14:17:24.358640 Self-elevating: D:\Claude Setup (2).exe --elevated --msix-path "C:\Users\sande\AppData\Local\Temp\Claude-2062474194.msix" --log-path "C:\Users\sande\AppData\Local\Temp\ClaudeSetup.log"
2026/07/01 14:17:26.724619 Waiting for elevated process to complete...
2026/07/01 14:17:26.731031 Log file: C:\Users\sande\AppData\Local\Temp\ClaudeSetup.log
2026/07/01 14:17:26.731031 === Claude Setup 2b3ab429b13f2c904d7552b7ca82a0d2a22af52f started ===
2026/07/01 14:17:26.732100 AllowDevelopmentWithoutDevLicense found with value: 1
2026/07/01 14:17:26.732100 Windows edition: Professional
2026/07/01 14:17:26.732100 Windows version: 10.0.26200
2026/07/01 14:17:26.732100 Native arch: x64
2026/07/01 14:17:26.732100 Elevation type: Full
2026/07/01 14:17:26.732100 Is elevated: true
2026/07/01 14:17:26.732100 Sideloading enabled: true
2026/07/01 14:17:26.732100 S Mode: false
2026/07/01 14:17:26.732100 Conflicting service: false
2026/07/01 14:17:26.732100 Running in elevated context
2026/07/01 14:17:26.732616 Installing MSIX from C:\Users\sande\AppData\Local\Temp\Claude-2062474194.msix (all-users: false)
2026/07/01 14:17:26.747084 Splash: 400x300, 8 frame(s), animated=true
2026/07/01 14:17:26.747084 System DPI: 144 (scale: 150%)
2026/07/01 14:17:26.769202 Verifying Authenticode signature on C:\Users\sande\AppData\Local\Temp\Claude-2062474194.msix
2026/07/01 14:17:27.235152 WinVerifyTrust: MSIX signature is valid
2026/07/01 14:17:27.435265 Signature verified: MSIX signer matches bootstrapper
2026/07/01 14:17:27.435890 Extracted family name from MSIX manifest: Claude_pzs8sxrjxfjjc
2026/07/01 14:17:27.435890 Squirrel process prefix: c:\users\sande\appdata\local\anthropicclaude\
2026/07/01 14:17:27.435890 Checking for running Squirrel Claude processes...
2026/07/01 14:17:27.441185 No Squirrel Claude processes found
2026/07/01 14:17:27.441185 Checking for existing Claude MSIX packages...
2026/07/01 14:17:27.461568 Installing MSIX: C:\Users\sande\AppData\Local\Temp\Claude-2062474194.msix
2026/07/01 14:17:27.461568 Standard install (not split-account), using AddPackage
2026/07/01 14:17:27.461568 Installing via AddPackage (current-user)...
2026/07/01 14:17:27.717821 MSIX installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CFF
2026/07/01 14:17:27.717821 ERROR dialog (opening log): Installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CFF

Please share this log with us.
2026/07/01 14:17:30.292405 Elevated process exited with code 1
2026/07/01 14:17:30.293397 Elevation failed: elevated installer exited with code 1
2026/07/01 14:17:30.293397 ERROR dialog (with log path): Administrator access is required to install Claude with full features. You can try again or install without Cowork.
2026/07/01 14:20:13.401999 Log file: C:\Users\sande\AppData\Local\Temp\ClaudeSetup.log
2026/07/01 14:20:13.402612 === Claude Setup 2b3ab429b13f2c904d7552b7ca82a0d2a22af52f started ===
2026/07/01 14:20:13.403124 AllowDevelopmentWithoutDevLicense found with value: 1
2026/07/01 14:20:13.403124 Windows edition: Professional
2026/07/01 14:20:13.403640 Windows version: 10.0.26200
2026/07/01 14:20:13.403640 Native arch: x64
2026/07/01 14:20:13.403640 Elevation type: Full
2026/07/01 14:20:13.403640 Is elevated: true
2026/07/01 14:20:13.403640 Sideloading enabled: true
2026/07/01 14:20:13.403640 S Mode: false
2026/07/01 14:20:13.403640 Conflicting service: false
2026/07/01 14:20:13.403640 Running in non-elevated context
2026/07/01 14:20:13.403640 User can elevate — installing MSIX directly
2026/07/01 14:20:13.419312 Splash: 400x300, 8 frame(s), animated=true
2026/07/01 14:20:13.419838 System DPI: 144 (scale: 150%)
2026/07/01 14:20:13.437631 MSIX URL: https://api.anthropic.com/api/desktop/win32/x64/msix/latest/redirect
2026/07/01 14:20:13.437631 Downloading MSIX to C:\Users\sande\AppData\Local\Temp\Claude-559428218.msix
2026/07/01 14:20:13.444926 proxy: WinHttpGetProxyForUrl("https://api.anthropic.com/api/desktop/win32/x64/msix/latest/redirect"): winapi error #12180
2026/07/01 14:20:14.024240 proxy: WinHttpGetProxyForUrl("https://downloads.claude.ai/releases/win32/x64/1.17377.1/Claude-2b3ab429b13f2c904d7552b7ca82a0d2a22af52f.msix"): winapi error #12180
2026/07/01 14:20:17.480602 Download progress: 10% (23428944 / 234211264 bytes)
2026/07/01 14:20:20.783053 Download progress: 20% (46857888 / 234211264 bytes)
2026/07/01 14:20:24.020576 Download progress: 30% (70269872 / 234211264 bytes)
2026/07/01 14:20:27.450686 Download progress: 40% (93698816 / 234211264 bytes)
2026/07/01 14:20:30.774357 Download progress: 50% (117111376 / 234211264 bytes)
2026/07/01 14:20:34.024811 Download progress: 60% (140540880 / 234211264 bytes)
2026/07/01 14:20:37.417977 Download progress: 70% (163953440 / 234211264 bytes)
2026/07/01 14:20:40.794208 Download progress: 80% (187382384 / 234211264 bytes)
2026/07/01 14:20:44.082603 Download progress: 90% (210794368 / 234211264 bytes)
2026/07/01 14:20:47.456985 Download progress: 100% (234211264 / 234211264 bytes)
2026/07/01 14:20:47.457900 Download complete: 234211264 bytes, SHA256: 553b9161d1913ed38dd2990d3d0ed9ce9cfbda2a2167dc17b9966e7ea809fb16
2026/07/01 14:20:47.457900 Download complete
2026/07/01 14:20:47.476907 Self-elevating: D:\Claude Setup (2).exe --elevated --msix-path "C:\Users\sande\AppData\Local\Temp\Claude-559428218.msix" --log-path "C:\Users\sande\AppData\Local\Temp\ClaudeSetup.log"
2026/07/01 14:20:47.618991 Waiting for elevated process to complete...
2026/07/01 14:20:47.624312 Log file: C:\Users\sande\AppData\Local\Temp\ClaudeSetup.log
2026/07/01 14:20:47.624910 === Claude Setup 2b3ab429b13f2c904d7552b7ca82a0d2a22af52f started ===
2026/07/01 14:20:47.625505 AllowDevelopmentWithoutDevLicense found with value: 1
2026/07/01 14:20:47.625505 Windows edition: Professional
2026/07/01 14:20:47.625505 Windows version: 10.0.26200
2026/07/01 14:20:47.625505 Native arch: x64
2026/07/01 14:20:47.625505 Elevation type: Full
2026/07/01 14:20:47.626075 Is elevated: true
2026/07/01 14:20:47.626075 Sideloading enabled: true
2026/07/01 14:20:47.626075 S Mode: false
2026/07/01 14:20:47.626075 Conflicting service: false
2026/07/01 14:20:47.626075 Running in elevated context
2026/07/01 14:20:47.626075 Installing MSIX from C:\Users\sande\AppData\Local\Temp\Claude-559428218.msix (all-users: false)
2026/07/01 14:20:47.640161 Splash: 400x300, 8 frame(s), animated=true
2026/07/01 14:20:47.640161 System DPI: 144 (scale: 150%)
2026/07/01 14:20:47.665582 Verifying Authenticode signature on C:\Users\sande\AppData\Local\Temp\Claude-559428218.msix
2026/07/01 14:20:48.134958 WinVerifyTrust: MSIX signature is valid
2026/07/01 14:20:48.335087 Signature verified: MSIX signer matches bootstrapper
2026/07/01 14:20:48.335872 Extracted family name from MSIX manifest: Claude_pzs8sxrjxfjjc
2026/07/01 14:20:48.335872 Squirrel process prefix: c:\users\sande\appdata\local\anthropicclaude\
2026/07/01 14:20:48.335872 Checking for running Squirrel Claude processes...
2026/07/01 14:20:48.340199 No Squirrel Claude processes found
2026/07/01 14:20:48.340199 Checking for existing Claude MSIX packages...
2026/07/01 14:20:48.361386 Installing MSIX: C:\Users\sande\AppData\Local\Temp\Claude-559428218.msix
2026/07/01 14:20:48.361386 Standard install (not split-account), using AddPackage
2026/07/01 14:20:48.361386 Installing via AddPackage (current-user)...
2026/07/01 14:20:48.618707 MSIX installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CFF
2026/07/01 14:20:48.618707 ERROR dialog (opening log): Installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CFF

Please share this log with us.
2026/07/01 14:28:31.841451 Elevated process exited with code 1
2026/07/01 14:28:31.842369 Elevation failed: elevated installer exited with code 1
2026/07/01 14:28:31.842369 ERROR dialog (with log path): Administrator access is required to install Claude with full features. You can try again or install without Cowork.
2026/07/01 14:43:10.754222 Log file: C:\Users\sande\AppData\Local\Temp\ClaudeSetup.log
2026/07/01 14:43:10.754739 === Claude Setup 2b3ab429b13f2c904d7552b7ca82a0d2a22af52f started ===
2026/07/01 14:43:10.755253 AllowDevelopmentWithoutDevLicense found with value: 1
2026/07/01 14:43:10.755253 Windows edition: Professional
2026/07/01 14:43:10.755767 Windows version: 10.0.26200
2026/07/01 14:43:10.755767 Native arch: x64
2026/07/01 14:43:10.755767 Elevation type: Full
2026/07/01 14:43:10.755767 Is elevated: true
2026/07/01 14:43:10.755767 Sideloading enabled: true
2026/07/01 14:43:10.755767 S Mode: false
2026/07/01 14:43:10.755767 Conflicting service: false
2026/07/01 14:43:10.755767 Running in non-elevated context
2026/07/01 14:43:10.755767 User can elevate — installing MSIX directly
2026/07/01 14:43:10.769825 Splash: 400x300, 8 frame(s), animated=true
2026/07/01 14:43:10.770352 System DPI: 144 (scale: 150%)
2026/07/01 14:43:10.789942 MSIX URL: https://api.anthropic.com/api/desktop/win32/x64/msix/latest/redirect
2026/07/01 14:43:10.789942 Downloading MSIX to C:\Users\sande\AppData\Local\Temp\Claude-3327014579.msix
2026/07/01 14:43:10.797853 proxy: WinHttpGetProxyForUrl("https://api.anthropic.com/api/desktop/win32/x64/msix/latest/redirect"): winapi error #12180
2026/07/01 14:43:11.429605 proxy: WinHttpGetProxyForUrl("https://downloads.claude.ai/releases/win32/x64/1.17377.1/Claude-2b3ab429b13f2c904d7552b7ca82a0d2a22af52f.msix"): winapi error #12180
2026/07/01 14:43:19.850226 Download progress: 10% (23428944 / 234211264 bytes)
2026/07/01 14:43:24.308130 Download progress: 20% (46857888 / 234211264 bytes)
2026/07/01 14:43:28.924121 Download progress: 30% (70269872 / 234211264 bytes)
2026/07/01 14:43:33.627388 Download progress: 40% (93698816 / 234211264 bytes)
2026/07/01 14:43:38.376584 Download progress: 50% (117111376 / 234211264 bytes)
2026/07/01 14:43:43.497354 Download progress: 60% (140540880 / 234211264 bytes)
2026/07/01 14:43:48.283798 Download progress: 70% (163953440 / 234211264 bytes)
2026/07/01 14:43:52.918541 Download progress: 80% (187382384 / 234211264 bytes)
2026/07/01 14:43:57.777536 Download progress: 90% (210794368 / 234211264 bytes)
2026/07/01 14:44:02.393840 Download progress: 100% (234211264 / 234211264 bytes)
2026/07/01 14:44:02.394918 Download complete: 234211264 bytes, SHA256: 553b9161d1913ed38dd2990d3d0ed9ce9cfbda2a2167dc17b9966e7ea809fb16
2026/07/01 14:44:02.395438 Download complete
2026/07/01 14:44:02.416784 Self-elevating: D:\Claude Setup (2).exe --elevated --msix-path "C:\Users\sande\AppData\Local\Temp\Claude-3327014579.msix" --log-path "C:\Users\sande\AppData\Local\Temp\ClaudeSetup.log"
2026/07/01 14:44:02.523867 Waiting for elevated process to complete...
2026/07/01 14:44:02.528949 Log file: C:\Users\sande\AppData\Local\Temp\ClaudeSetup.log
2026/07/01 14:44:02.529550 === Claude Setup 2b3ab429b13f2c904d7552b7ca82a0d2a22af52f started ===
2026/07/01 14:44:02.530148 AllowDevelopmentWithoutDevLicense found with value: 1
2026/07/01 14:44:02.530148 Windows edition: Professional
2026/07/01 14:44:02.530148 Windows version: 10.0.26200
2026/07/01 14:44:02.530148 Native arch: x64
2026/07/01 14:44:02.530148 Elevation type: Full
2026/07/01 14:44:02.530701 Is elevated: true
2026/07/01 14:44:02.530701 Sideloading enabled: true
2026/07/01 14:44:02.530701 S Mode: false
2026/07/01 14:44:02.530701 Conflicting service: false
2026/07/01 14:44:02.530701 Running in elevated context
2026/07/01 14:44:02.530701 Installing MSIX from C:\Users\sande\AppData\Local\Temp\Claude-3327014579.msix (all-users: false)
2026/07/01 14:44:02.544721 Splash: 400x300, 8 frame(s), animated=true
2026/07/01 14:44:02.544721 System DPI: 144 (scale: 150%)
2026/07/01 14:44:02.569558 Verifying Authenticode signature on C:\Users\sande\AppData\Local\Temp\Claude-3327014579.msix
2026/07/01 14:44:03.081313 WinVerifyTrust: MSIX signature is valid
2026/07/01 14:44:03.313036 Signature verified: MSIX signer matches bootstrapper
2026/07/01 14:44:03.313734 Extracted family name from MSIX manifest: Claude_pzs8sxrjxfjjc
2026/07/01 14:44:03.313734 Squirrel process prefix: c:\users\sande\appdata\local\anthropicclaude\
2026/07/01 14:44:03.313734 Checking for running Squirrel Claude processes...
2026/07/01 14:44:03.318476 No Squirrel Claude processes found
2026/07/01 14:44:03.318476 Checking for existing Claude MSIX packages...
2026/07/01 14:44:03.337650 Installing MSIX: C:\Users\sande\AppData\Local\Temp\Claude-3327014579.msix
2026/07/01 14:44:03.337650 Standard install (not split-account), using AddPackage
2026/07/01 14:44:03.337650 Installing via AddPackage (current-user)...
2026/07/01 14:44:03.594980 MSIX installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CFF
2026/07/01 14:44:03.594980 ERROR dialog (opening log): Installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CFF

Please share this log with us.
2026/07/01 14:44:36.137604 Elevated process exited with code 1
2026/07/01 14:44:36.137604 Elevation failed: elevated installer exited with code 1
2026/07/01 14:44:36.137604 ERROR dialog (with log path): Administrator access is required to install Claude with full features. You can try again or install without Cowork.
2026/07/01 14:52:14.939212 Log file: C:\Users\sande\AppData\Local\Temp\ClaudeSetup.log
2026/07/01 14:52:14.939212 === Claude Setup 2b3ab429b13f2c904d7552b7ca82a0d2a22af52f started ===
2026/07/01 14:52:14.940433 AllowDevelopmentWithoutDevLicense found with value: 1
2026/07/01 14:52:14.940433 Windows edition: Professional
2026/07/01 14:52:14.940433 Windows version: 10.0.26200
2026/07/01 14:52:14.940433 Native arch: x64
2026/07/01 14:52:14.940433 Elevation type: Full
2026/07/01 14:52:14.940433 Is elevated: true
2026/07/01 14:52:14.940433 Sideloading enabled: true
2026/07/01 14:52:14.940433 S Mode: false
2026/07/01 14:52:14.940433 Conflicting service: false
2026/07/01 14:52:14.940433 Running in non-elevated context
2026/07/01 14:52:14.940433 User can elevate — installing MSIX directly
2026/07/01 14:52:14.955701 Splash: 400x300, 8 frame(s), animated=true
2026/07/01 14:52:14.955701 System DPI: 144 (scale: 150%)
2026/07/01 14:52:14.976479 MSIX URL: https://api.anthropic.com/api/desktop/win32/x64/msix/latest/redirect
2026/07/01 14:52:14.976479 Downloading MSIX to C:\Users\sande\AppData\Local\Temp\Claude-3460405028.msix
2026/07/01 14:52:14.983792 proxy: WinHttpGetProxyForUrl("https://api.anthropic.com/api/desktop/win32/x64/msix/latest/redirect"): winapi error #12180
2026/07/01 14:52:15.173043 proxy: WinHttpGetProxyForUrl("https://downloads.claude.ai/releases/win32/x64/1.17377.1/Claude-2b3ab429b13f2c904d7552b7ca82a0d2a22af52f.msix"): winapi error #12180
2026/07/01 14:52:19.741145 Download progress: 10% (23428944 / 234211264 bytes)
2026/07/01 14:52:24.367521 Download progress: 20% (46857888 / 234211264 bytes)
2026/07/01 14:52:28.630606 Download progress: 30% (70269872 / 234211264 bytes)
2026/07/01 14:52:32.290517 Download progress: 40% (93698816 / 234211264 bytes)
2026/07/01 14:52:35.555119 Download progress: 50% (117111376 / 234211264 bytes)
2026/07/01 14:52:39.021615 Download progress: 60% (140540880 / 234211264 bytes)
2026/07/01 14:52:42.317395 Download progress: 70% (163969824 / 234211264 bytes)
2026/07/01 14:52:45.550374 Download progress: 80% (187382384 / 234211264 bytes)
2026/07/01 14:52:48.925209 Download progress: 90% (210794368 / 234211264 bytes)
2026/07/01 14:52:52.236673 Download progress: 100% (234211264 / 234211264 bytes)
2026/07/01 14:52:52.237323 Download complete: 234211264 bytes, SHA256: 553b9161d1913ed38dd2990d3d0ed9ce9cfbda2a2167dc17b9966e7ea809fb16
2026/07/01 14:52:52.237323 Download complete
2026/07/01 14:52:52.255641 Self-elevating: D:\Claude Setup (2).exe --elevated --msix-path "C:\Users\sande\AppData\Local\Temp\Claude-3460405028.msix" --log-path "C:\Users\sande\AppData\Local\Temp\ClaudeSetup.log"
2026/07/01 14:52:52.400558 Waiting for elevated process to complete...
2026/07/01 14:52:52.405633 Log file: C:\Users\sande\AppData\Local\Temp\ClaudeSetup.log
2026/07/01 14:52:52.406238 === Claude Setup 2b3ab429b13f2c904d7552b7ca82a0d2a22af52f started ===
2026/07/01 14:52:52.406847 AllowDevelopmentWithoutDevLicense found with value: 1
2026/07/01 14:52:52.406847 Windows edition: Professional
2026/07/01 14:52:52.407503 Windows version: 10.0.26200
2026/07/01 14:52:52.407503 Native arch: x64
2026/07/01 14:52:52.407503 Elevation type: Full
2026/07/01 14:52:52.407503 Is elevated: true
2026/07/01 14:52:52.407503 Sideloading enabled: true
2026/07/01 14:52:52.407503 S Mode: false
2026/07/01 14:52:52.407503 Conflicting service: false
2026/07/01 14:52:52.407503 Running in elevated context
2026/07/01 14:52:52.407503 Installing MSIX from C:\Users\sande\AppData\Local\Temp\Claude-3460405028.msix (all-users: false)
2026/07/01 14:52:52.422459 Splash: 400x300, 8 frame(s), animated=true
2026/07/01 14:52:52.422459 System DPI: 144 (scale: 150%)
2026/07/01 14:52:52.439486 Verifying Authenticode signature on C:\Users\sande\AppData\Local\Temp\Claude-3460405028.msix
2026/07/01 14:52:52.932090 WinVerifyTrust: MSIX signature is valid
2026/07/01 14:52:53.147918 Signature verified: MSIX signer matches bootstrapper
2026/07/01 14:52:53.148445 Extracted family name from MSIX manifest: Claude_pzs8sxrjxfjjc
2026/07/01 14:52:53.148445 Squirrel process prefix: c:\users\sande\appdata\local\anthropicclaude\
2026/07/01 14:52:53.148445 Checking for running Squirrel Claude processes...
2026/07/01 14:52:53.153359 No Squirrel Claude processes found
2026/07/01 14:52:53.153359 Checking for existing Claude MSIX packages...
2026/07/01 14:52:53.176128 Installing MSIX: C:\Users\sande\AppData\Local\Temp\Claude-3460405028.msix
2026/07/01 14:52:53.176128 Standard install (not split-account), using AddPackage
2026/07/01 14:52:53.176128 Installing via AddPackage (current-user)...
2026/07/01 14:52:53.432522 MSIX installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CFF
2026/07/01 14:52:53.433132 ERROR dialog (opening log): Installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CFF

Please share this log with us.
2026/07/01 14:53:15.561049 Elevated process exited with code 1
2026/07/01 14:53:15.561049 Elevation failed: elevated installer exited with code 1
2026/07/01 14:53:15.561049 ERROR dialog (with log path): Administrator access is required to install Claude with full features. You can try again or install without Cowork.

What Should Happen?

Fix it I need cowork! If you can write a script to fix it please do

Error Messages/Logs

Cowork Sessions Backup — 2026-07-01
Consolidated from 9 local Cowork sessions, pulled via session-transcript inspection ahead of a possible sign-out. This is a plain-text record independent of the Cowork app — keep this file itself backed up somewhere outside Cowork (email it to yourself, drop it in Drive/Dropbox) since the whole point is not to depend on the app's own persistence.
Gaps are flagged explicitly below — don't assume silence means "nothing there."
---
1. Polymers — PE/PP decolorization (session: "PE/PP polymers discussion")
Engineering design, IP-clean, two-mechanism decolorization train:
Mechanism A — coagulation + depth filtration, for colloidal pigment/carbon black.
Mechanism B — adsorption via bleaching clay + activated carbon, for dissolved dye/chromophore.
Anchor patent: US 3,232,891 (1966, expired) — mineral-acid coagulation route, deliberately used because it's out of patent.
Membrane note: polymeric OSN (organic solvent nanofiltration) membranes only rated to ~50°C; hot duty (150°C) needs ceramic membranes (e.g. Inopor). ePTFE/Gore-Tex is hot microfiltration media, not nanofiltration — don't conflate the two.
16-route parametric model (R1–R16) built in Excel with toggleable capacity/cost drivers, validated to zero formula errors, Dashboard + Comparison tabs.
Files (on `C:\\innovation-team\\...`):
`PE-PP\_petroleum-ether\_dissolution\_reconstruction.md` — core 7-step process design doc.
`Decolorisation\_findings\_PE-PP.docx` — zeolite/bentonite trial findings + inerted-blank-run diagnostic recommendation.
`PE-PP\_Acid\_Coagulation\_Route.docx` — standalone route doc, confirmed on disk.
Excel parametric model (R1–R16) + matching Word proposal — saved in the innovation-team folder (exact filename not captured in this pass; open the folder directly to confirm).
`Contract reviews` subfolder — prior contract reviews (EN + NL).
---
2. SolarAirco (session: "Solarairco files organization")
Engineering design: solar-driven liquid-desiccant HVAC + atmospheric water generation (AWG). Psychrometric/heat-balance modeling; COP_th vs COP_el kept distinct. Main efficiency lever identified: internally-cooled absorber / internally-heated regenerator (Blue Frontier-style design), with a solid desiccant wheel as the lower-risk fallback benchmark.
Files (moved to the correct project folder after an initial misfile):
`D:\\Documents\\my documents\\Documenten\\SolarAirco\\Solarairco Cowork\\SolarARCO\_5kW\_design\_model.xlsx`
`D:\\Documents\\my documents\\Documenten\\SolarAirco\\Solarairco Cowork\\SolarARCO\_5kW\_design\_report\_REV2.docx` (982 KB, final — has embedded Figure 1 system schematic, Figure 2 heat rejection loop, Appendix B with 3 legacy concept drawings B1–B3 flagged as the superseded membrane-based design, don't build off those).
`solarairco\_calc.py` — CoolProp reference model, cross-validated the Excel psychrometrics via the Magnus formula to ~1% agreement.
Note: the original REV file couldn't overwrite in place because Word had it locked — REV2 is the current one. Close Word before touching the original filename.
---
3. Modeling / "Green Modem" (sessions: "Modeling" + "Desktop Claude folder" — same underlying project)
This is the GreenModem project — a DWSIM SYNGAS flowsheet model of what's described as your father's design (endothermic, efficient reaction philosophy). This is almost certainly what you meant by "Green Modem."
Key technical finding (important — changes what to trust in the model): DWSIM's property package gives solid graphite a nonphysical enthalpy (≈ −93,307 kJ/kg), which throws off any heat duty number from a block containing solid graphite (a char-temperature clamp test showed a spurious −85.9 kW vs a real ~9.5 kW expected). Verdict: trust DWSIM for the species/atom balance (100% closure confirmed), do not trust DWSIM for heat duty around solid graphite — use Cantera for that. Rule going forward: keep char as a separate solid stream, no downstream Heater clamp on it.
Files:
`C:\\innovation-team\\GreenModem\_DWSIM\_Continuity\_Handoff.md` — living handoff doc. §10 records the graphite/energy-basis finding above. §11 "NEXT SESSION, START HERE" is the resume block: next step is wiring R-103/R-104 (build #30) with species from DWSIM + energy from Cantera, then validating against Cantera at 591 kg/h (#31).
`C:\\innovation-team\\GreenModem\_Mk2\_Engineering\_Package\_2026-06-30\\02\_DWSIM\_model\_v5\\START\_IN\_DWSIM.docx` (9.8 KB) — validated deliverable confirmed on disk (the in-app file card failed to render for this one due to a path-translation bug in the `present\_files` tool, not a missing/broken file — open it directly from that path).
Gap: I could not find a session or file literally named "greenXs" anywhere across all 9 sessions. If that's a distinct project from GreenModem, it isn't captured here — point me to it (a folder path or a rough description) and I'll go pull it specifically.
---
4. Legal — Sinko Hydrocat / OBBO TEC / Hydrocat (session: "Sinko Hydrocat term sheet assessment")
Contract: Schedule 4.1(c) SPA — Hydrocat Technology B.V. (transfer of contract sublicense), draft version 61760105.x. Entities: Indigo Energy C.V. (your side), OBBO TEC B.V., HYDROCAT B.V. Chain of title: Indigo → OBBOTEC → Hydrocat. Governing law / forum: Rechtbank Rotterdam.
Three open negotiation points sent back on this draft:
10% one-time fee (art. 4.3) — needs to be anchored to the first unit built, operationally (in clause 2.2, not just the recital), regardless of what label the buyer puts on it (pilot/demo/prototype/pre-commercial/commercial) — closes the "just call it commercial and skip the fee" escape route. Drafted clause text was produced and sent (see full transcript for exact English wording).
Date order problem: Head License dated 23 June 2021 but the sublicense it supposedly rests on is dated 20 July 2020 — sublicense predates the license it's based on. Flagged for confirmation + a ratification recital to close the chain.
Loose ends in the draft: "Assumed Obligations" (clause 7.1) used but never defined; Schedule 1 referenced in 7.2(c) but missing from the draft; signature blocks still blank ("[]").
Premortem note already flagged to you: the fee trigger is now locked down, but the fee basis (art. 4.3, "directly attributable third-party out-of-pocket costs") is not — the buyer can still steer toward a cheaper "commercial" design to shrink the cost base the 10% is calculated on. That was your deliberate choice, just keep it in view for the call.
Folder: `D:\\...\\OBBO TEC b.v\\HYDROCAT B.V\\Sub-Licentie Overeenkomst\\Sch. 4.1(c) SPA - Hydrocat Technology B.V. (transfer of contract sublicense) \[DRAFT](61760105.3) (1).docx`, plus prior EN/NL reviews under `C:\\innovation-team\\Contract reviews`.
---
5. Other sessions checked (context, not priority topics but relevant)
"Recent discussions restore" — this session is itself a record of a prior instance of the exact problem you're worried about now: Cowork projects disappeared from the app. Diagnosis found the underlying data was NOT wiped (LevelDB store on disk still had real content, including your saved Claude custom instructions), but the app's own project index (`git-worktrees.json`) had gone empty, which is why nothing showed up in the UI — described as an acknowledged research-preview limitation, not something fixable from inside a session. A `D:\\Desktop\\Claude` folder was made as a safe copy of the raw data at that time. Recommendation carried over from that session: don't reinstall or reset Cowork, and file this with Anthropic support (thumbs-down + support.claude.com) with that copy attached — only they can do a server-side restore.
"What needs my attention" — attempted a live status-page artifact; blocked because only Google Drive, Lucid, and Canva are actually authenticated (Slack/Linear/Notion/Fireflies/email/calendar are not connected). Not resumed.
"My Passport HDD organization" — cosmetic Explorer folder-view fix (set Content view, applied to all folders of that type). No content risk here.
---
What this file does and doesn't cover
This captures file paths, entities, key decisions, and open items — enough to reconstruct where each project stands even if a Cowork session's chat history disappears. It is not a full verbatim transcript; for exact wording (e.g. the full drafted legal clause, or the complete DWSIM probe sequence), the source sessions still have it, and this

Steps to Reproduce

Environment: Windows 11 Pro, build 10.0.26200 (x64), Developer Mode enabled, sideloading enabled (AllowDevelopmentWithoutDevLicense = 1), S Mode off, UAC/elevation functioning normally (confirmed Is elevated: true in logs).
Have Claude Desktop already installed via MSIX (version 1.6608.2.0, package family Claude_pzs8sxrjxfjjc) and previously functioning normally.
Trigger an update/reinstall to a newer version (in this case 1.17377.1) via ClaudeSetup.exe, either through the app's own updater or by running the installer manually. Approve the UAC elevation prompt when requested.
Observe the installer log (%TEMP%\ClaudeSetup.log) shows:

MSIX downloaded and Authenticode signature verified successfully
Attempted removal of the existing package: RemovePackage failed with HRESULT 0x80073CFA (fails twice — both current-user and default scope)
Installer proceeds to AddPackage anyway despite the failed removal
AddPackage failed: AddPackage failed with HRESULT 0x80073CFF

Installation fails with dialog: "Installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CFF."
To rule out leftover/orphaned state as the cause, perform full manual cleanup (all commands run in an elevated, 64-bit PowerShell session):

powershell# Confirm no package is registered via normal enumeration
Get-AppxPackage -Name "Claude" -AllUsers | Format-List Name, PackageFullName, Status

→ returns nothing

Check for orphaned package folder despite empty Get-AppxPackage result

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

→ Claude_1.6608.2.0_x64__pzs8sxrjxfjjc found on disk, invisible to Get-AppxPackage

Remove the orphaned registration

Remove-AppxPackage -Package "Claude_1.6608.2.0_x64__pzs8sxrjxfjjc" -AllUsers

→ succeeds silently

Confirm permissions are not the issue

icacls "C:\Program Files\WindowsApps\Claude_1.6608.2.0_x64__pzs8sxrjxfjjc"

→ standard AppX ACLs, TrustedInstaller owner, no anomalies

Check per-user app data / sandbox folder

Get-ChildItem "$env:LOCALAPPDATA\Packages" -Directory | Where-Object { $_.Name -like "Claude" }

→ Claude_pzs8sxrjxfjjc present, containing LocalCache\Roaming and SystemAppData\Helium (User.dat, UserClasses.dat)

Identify and kill process locking a file in that folder

Get-Process | Where-Object { $_.Path -like "chrome-native-host" }

→ chrome-native-host.exe still running from old install

Stop-Process -Id <PID> -Force

Remove the per-user data folder

Remove-Item "$env:LOCALAPPDATA\Packages\Claude_pzs8sxrjxfjjc" -Recurse -Force

→ succeeds

Check remaining locations

Get-ChildItem "$env:LOCALAPPDATA\AnthropicClaude" # → empty (no old Squirrel install)
Get-ChildItem "HKCU:\Software\Classes\Local Settings\Software\Microsoft\Windows\CurrentVersion\AppModel\SystemAppData" | Where-Object { $_.Name -like "Claude" } # → no entry
Get-StartApps | Where-Object { $_.Name -like "Claude" } # → no ghost Start Menu entry (only unrelated Chrome extension)

Confirm the system is now fully clean — no package registration, no per-user data, no locking processes, no Start Menu ghosts anywhere Windows tracks Claude Desktop.
Re-run ClaudeSetup.exe on this fully clean system.
Result: Installer log shows Checking for existing Claude MSIX packages... immediately followed by AddPackage failed: AddPackage failed with HRESULT 0x80073CFF — no removal step is even attempted (nothing left to remove), and AddPackage still rejects the package in under 0.3 seconds. Identical failure to step 5, with zero local state remaining.

Expected behavior: AddPackage should successfully register the MSIX package on a system with no conflicting registrations, correct permissions, no locked files, and a validated signature.
Actual behavior: AddPackage fails immediately with HRESULT 0x80073CFF regardless of local system state.
Files attached: ClaudeSetup.log (full session log covering both the original failure and the post-cleanup reproduction attempt).

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

don't know

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_

View original on GitHub ↗

This issue has 2 comments on GitHub. Read the full discussion on GitHub ↗