Clash Won't Open or the Core Fails to Start? A Triage Guide

When the client suddenly will not open or connect, it is almost always one of four problems. Work through them in order.

Port already in use

A log line like bind: address already in use means another program (usually a second proxy tool) holds port 7890. Close the conflicting app, or change the port in settings.

Core fails to start

• Config syntax error: switch to the default profile — if it starts, blame the subscription config
• Antivirus quarantined the core binary: restore it and add an exclusion
• TUN service not authorized: reinstall service mode and approve the prompt

UI problems

A white window on Windows usually means a broken WebView2 runtime — reinstall it. Tray icon gone but process alive: restart the client or log out and back in.

The nuclear option

Full uninstall, delete the config directory, reinstall — clears 95% of stubborn cases. Back up your subscription link first.