The log says listen tcp 127.0.0.1:7897: address already in use, or the system proxy toggle bounces back off — same disease: something else grabbed Clash's port first. Three steps to locate it, two ways to fix it.

Using netstat to find the process occupying port 7897 and killing it
netstat gives the PID, tasklist names it, taskkill ends it

Step 1: Identify the squatter

Windows — open a command prompt:

netstat -ano | findstr 7897

The last column is the PID (say 14232). Name it:

tasklist /FI "PID eq 14232"

macOS / Linux get it in one shot:

lsof -i :7897

Step 2: Decide who moves

Case A: it is another proxy app

The most common finding. Clash for Windows, v2rayN and friends use neighboring default ports; running two at once guarantees a collision. Fully quit the other one — check the tray, they linger there — then restart Clash Verge. Long-term, one proxy client per machine is the sane setup; ex-CFW users have a migration guide.

Case B: it is a leftover verge-mihomo process

A previous session did not exit cleanly and the old core still owns the port. Task Manager (Ctrl+Shift+Esc) → find verge-mihomo → end it, then relaunch. Or from the command line:

taskkill /IM verge-mihomo.exe /F

Case C: it is legitimate software you need

Do not kill it — move Clash instead. Next step.

Step 3 (optional): Move Clash Verge to another port

Settings → Port settings → change the mixed port from 7897 to something obscure like 17890. The core restarts on save. Two ripple effects to remember:

  • The system proxy follows automatically — nothing to do there;
  • Anything configured by hand must be updated: browser extensions, terminal environment variables, and any LAN devices pointing at this machine.

Preventing round two

  1. Uninstall proxy clients you no longer use — especially ones that autostart and re-grab the port at boot;
  2. Download managers and local dev servers occasionally land on 7897 by chance; parking Clash on an uncommon port ends the lottery;
  3. If the port error comes with a repeatedly restarting core, the port may not be the whole story — continue with startup troubleshooting.