keep getting "? Something is already running on port 3000" when I do npm start on react app

javascript macos npm terminal server
Jonathan Lee picture Jonathan Lee · Feb 28, 2018 · Viewed 19.5k times · Source

I keep on getting "? Something is already running on port 3000" message in my terminal when I start up my react server when there is absolutely nothing running on my port 3000

What I have tried to solve with:

  1. Restart the macOS.
  2. checking my "http://localhost:3000" on chrome browser. ( Nothing: This site can’t be reached )
  3. Go to chrome://serviceworker-internals and chrome://appcache-internals, search for localhost:3000 ( Nothing found )
  4. I also tried almost every command lines I found on Google regarding this issue
  5. I also created another express.js app, and it was successfully launch on port:3000 while React said there is something running on 3000. React on my computer just keeping thinking there is something running on port:3000...

terminal

Chrome

Answer

Muneeb picture Muneeb · Feb 28, 2018

Open cmd and write this

netstat -a -o -n

You will get list of active connections then find 3000 by hitting

Cntrl + f

enter image description here

Copy the PID of that port and hit this command

taskkill /F /PID PID_of_port

enter image description here

Edit This guide is for windows.

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