[BUG] Claude Desktop crashes on startup after auto-update on Windows with Korean (non-ASCII) username

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?

Claude Desktop on Windows crashes immediately after startup (window appears for 1-2 seconds then closes) following an automatic update from v1.1.3963 to v1.1.4088.

Two critical issues found in main.log:

1. Korean (non-ASCII) username path encoding failure: Windows username '김용락' is corrupted to '源?⑸씫' throughout the app's internal path resolution.

1. Hardware virtualization check false negative: lam_hardware_virt_check reports is_enabled: false, despite all Hyper-V features being confirmed Enabled via Get-WindowsOptionalFeature and HyperVisorPresent: True via Get-ComputerInfo.

The app silently exits after the blocked permission check for 'background-sync' with no error dialog shown to the user. This affects all Windows users with non-ASCII usernames (Korean, Japanese, Chinese, Arabic, etc.).

What Should Happen?

1. Claude Desktop should correctly handle Unicode/non-ASCII characters in Windows usernames and file paths.
2. The lam_hardware_virt_check should accurately detect virtualization status regardless of username encoding.
3. If the app detects a startup failure, it should display a meaningful error message instead of silently closing.
4. Auto-updates should not break existing working installations.

Error Messages/Logs

2026-02-24 11:31:37 [info] [EventLogging] Queuing event: lam_hardware_virt_check | metadata: {
  cpu_model: 'Intel(R) Core(TM) i7-10700 CPU @ 2.90GHz',
  total_memory: 17100894208,
  is_enabled: false
}
2026-02-24 11:31:37 [info] Loaded 1 persisted sessions from C:\Users\源?⑸씫\AppData\Roaming\Claude\local-agent-mode-sessions\...
2026-02-24 11:31:37 [info] [oauth] token cache location: C:\Users\源?⑸씫\AppData\Roaming\Claude\config.json
2026-02-24 11:31:38 [warn] Blocked permission check {
  permission: 'background-sync',
  requestingOrigin: 'https://a.claude.ai/',
  requestingUrl: 'about:blank'
}
// Log ends here. App silently exits with no error.

Steps to Reproduce

1. Set up Windows 11 with a Korean username (e.g., '김용락')
2. Install Claude Desktop (MSIX package) - works normally on v1.1.3963
3. Allow auto-update to v1.1.4088
4. Launch Claude Desktop
5. Window appears for 1-2 seconds, then silently closes
6. No error message is displayed

Workaround: Complete uninstall, delete residual data, and reinstall:

• Get-AppxPackage Claude | Remove-AppxPackage
• taskkill /f /im chrome-native-host.exe
• rmdir /s /q "%LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc"
• rmdir /s /q "%APPDATA%\Claude"
• Reinstall from https://claude.ai/download

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

1.1.3963

Claude Code Version

Claude Desktop 1.1.4088 (MSIX package)

Platform

Other

Operating System

Windows

Terminal/Shell

Other

Additional Information

Environment:

• Windows 11 Pro (Build 10.0.26200)
• Architecture: x64
• CPU: Intel Core i7-10700 @ 2.90GHz
• RAM: 16GB
• Windows Username: 김용락 (Korean characters)

Key findings:

• The username '김용락' is corrupted to '源?⑸씫' in all internal path references
• This likely affects millions of users in East Asia (Korea, Japan, China) who use native characters in Windows usernames
• v1.1.3963 worked perfectly for 2 days before auto-update broke it
• Cache clearing alone does not fix the issue; full reinstall is required

Suggestions:

1. Use UTF-8 encoding for all internal path handling on Windows
2. Test with non-ASCII usernames as part of release QA
3. Add pre-update compatibility check before applying auto-updates
4. Provide rollback mechanism when auto-updates cause failures
5. Show error dialogs instead of silent crashes