Claude Code Web crashes on startup with 'An error occurred while executing Claude Code'

Description

Claude Code Web (Research Preview) consistently crashes during startup when connecting to a private GitHub repository. The error occurs at various phases of initialization (Ideating, Perusing, Flibbertigibbeting) but always results in the same error message.

Error Message

An error occurred while executing Claude Code. You can try again by sending a new message or starting a new session.

Environment

• Platform: Claude Code Web (claude.ai/code)
• Browser: Safari (macOS)
• Repository: Private GitHub repo (~70 files in .claude/ directory)
• Date: 2026-01-16

Steps to Reproduce

1. Go to claude.ai/code
2. Connect to the GitHub repository
3. Start a new session with any prompt
4. Observe crash during initialization phase

What Was Tried

• ✅ Cleared browser cache
• ✅ Started fresh sessions
• ✅ Removed $schema URL from .claude/settings.json
• ✅ Verified mcp.json has empty mcpServers: {}
• ✅ Reduced CLAUDE.md to minimal content (17 lines)
• ✅ Verified all JSON files are valid

None of these resolved the issue.

Configuration Files

.claude/settings.json (validated):

{
  "permissions": {
    "allow": [],
    "deny": [
      "Bash(*--no-verify*)",
      "Bash(git push --force*)",
      "Bash(git push -f*)",
      "Bash(rm -rf /*)",
      "Bash(sudo rm*)"
    ],
    "defaultMode": "bypassPermissions"
  }
}

.claude/mcp.json:

{
  "mcpServers": {}
}

Notes

• CLI and VSCode extension work fine with the same repository
• The crash happens at different initialization phases but always crashes
• This suggests a server-side issue rather than configuration

Expected Behavior

Claude Code Web should start successfully and allow interaction with the repository.