Answers for "Port 3000 is already in use."

Something is already running on port 3000.

npx kill-port 3000 8080 4200

Port 3000 is already in use, but when I try to kill nothing is found

netstat -ano | findstr :3000
taskkill /PID "123" /F

Port 3000 is already in use.

If this error is in nextjs

in package.json, update scripts:
"dev": "PORT=3001 next dev",

you can choose other port, and also change for start.

stop npm running on port 3000

netstat -ano | findstr :3000
taskkill /F /PID PID_of_port

Something is already running on port 3000

npx kill-port 3000 8080 4200

Node.js Port 3000 already in use but it actually isn't?

$ lsof -i tcp:3000
$ kill -9 PID