[BUG] MSIX AddPackage hangs/times out on Windows 11 Build 26200.8039 — was working on same build days earlier

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: [BUG] MSIX AddPackage hangs/times out on Windows 11 Build 26200.8039 — was working on same build (.7714) days earlier

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Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report
• [x] I am using the latest version of Claude Code

What's Wrong?

MSIX AddPackage consistently times out (5+ minutes) on Windows 11 Home 25H2 Build 26200.8039. The same machine successfully installed Claude Desktop via MSIX on the same base build (26200) just 9 days earlier with no issues.

Key Evidence from ClaudeSetup.log

Working (March 13, 2026 — Build 26200):

2026/03/13 18:28:14.936839 Installing via AddPackage (current-user)...
2026/03/13 18:28:21.189190 MSIX package installed successfully

→ 7 seconds to complete.

Working (March 13, 2026 — second install with CoworkVMService conflict):

2026/03/13 19:05:14.520897 Installing via AddPackage (current-user)...
2026/03/13 19:05:45.771916 MSIX package installed successfully

→ 31 seconds to complete.

Working (March 16, 2026):

2026/03/16 05:55:23.685030 Installing via AddPackage (current-user)...
2026/03/16 05:55:55.185938 MSIX package installed successfully

→ 32 seconds to complete.

Working (March 22, 2026 14:55 — before Windows Update applied):

2026/03/22 14:55:49.299300 Installing via AddPackage (current-user)...
2026/03/22 14:55:49.799571 MSIX package installed successfully

→ 0.5 seconds to complete.

Working (March 22, 2026 15:15):

2026/03/22 15:15:36.707807 Installing via AddPackage (current-user)...
2026/03/22 15:15:37.208730 MSIX package installed successfully

→ 0.5 seconds to complete.

BROKEN (March 22, 2026 16:01+ — after Windows Update to .8039):

2026/03/22 16:01:55.349148 Installing via AddPackage (current-user)...
2026/03/22 16:04:06.718474 MSIX installation failed: AddPackage failed: AddPackage failed with HRESULT 0x80073CF8

2026/03/22 16:04:17.338502 Installing via AddPackage (current-user)...
2026/03/22 16:06:47.753997 MSIX installation failed: AddPackage failed: AddPackage timed out after 5 minutes

Every subsequent attempt on .8039 also fails with timeout or 0x80073CF8.

What was tried (all failed on .8039)

• Add-AppxPackage with -ForceApplicationShutdown -ForceUpdateFromAnyVersion
• Add-AppxPackage after enabling Developer Mode
• DISM /Online /Cleanup-Image /RestoreHealth (completed successfully, found/repaired corrupt files)
• sfc /scannow (found and repaired corrupt files)
• wsreset.exe
• AppX Deployment Service restart
• Removing all Claude MSIX packages (Get-AppxPackage *claude* returns nothing)
• Disabling ESET antivirus real-time protection
• Full PC reboot between attempts
• Multiple fresh downloads of ClaudeSetup.exe

AppX Event Log Details

Error 0x80073CF6: パッケージを登録できません: Claude_pzs8sxrjxfjjc
Error 0x80073D05: 内部エラー
Error 0x80073CF8: ユーザーによってインストール要求が取り消されました

Package folder was being moved to C:\Program Files\WindowsApps\Deleted\ during failed attempts.

Workaround Found

Manually extracting the MSIX as a ZIP and running claude.exe directly works for basic Chat/Code functionality, but Cowork is not available without proper MSIX registration.

Environment

• OS: Windows 11 Home 25H2
• Build: 26200.8039 (Windows Insider)
• Previous working build: 26200 (minor version unknown, but .8039 update was applied on March 22)
• CPU: x64
• Claude Desktop version: Latest from claude.ai/download (March 22, 2026)
• Antivirus: ESET (disabled during testing — no effect)

Expected Behavior

MSIX AddPackage should complete within seconds (as it did on the same base build before the .8039 update).

Actual Behavior

AddPackage hangs indefinitely (30+ minutes with manual Add-AppxPackage) or times out after the 5-minute limit in ClaudeSetup.exe.

Suggestion

Consider increasing the AddPackage timeout or implementing a retry mechanism. The 5-minute hard timeout may be too aggressive for some Windows configurations. Additionally, a fallback installation mode that doesn't require MSIX registration (similar to the manual extraction workaround) would help users on affected Windows builds retain access to Cowork.

Related Issues

• #25136 — Cowork tab not showing on Windows 11 Pro x64 Build 26200
• #25914 — CoworkVMService crashes during HCS DLL initialization on Build 26200
• #27652 — Cowork regression: HcnCreateNetwork fails on Build 26200
• #29322 — Cowork VM marked unsupported on Build 26200

What Should Happen?

MSIX AddPackage should complete within seconds, as it did on the same build before the .8039 update (0.5-31 seconds in logs). Claude Desktop with Cowork should install and function normally.

Error Messages/Logs

2026/03/22 17:50:28.499637 MSIX installation failed: AddPackage failed: AddPackage timed out after 5 minutes
ERROR dialog: Installation failed: AddPackage failed: AddPackage timed out after 5 minutes
AppX Event Log errors: 0x80073CF6 (package registration failed), 0x80073D05 (internal error), 0x80073CF8 (install request cancelled by user)
Previously working: 2026/03/22 15:15 installed in 0.5 seconds on same build before Windows Update to .8039

Steps to Reproduce

1. Install Claude Desktop on Windows 11 Build 26200 (MSIX installs successfully)
2. Apply Windows Update to Build 26200.8039
3. Run ClaudeSetup.exe from claude.ai/download
4. MSIX AddPackage hangs and times out after 5 minutes
5. Manual Add-AppxPackage also hangs indefinitely (30+ minutes)

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

1.1.7714.0

Claude Code Version

N/A - this is a Claude Desktop MSIX installation issue, not Claude Code

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_