listen EADDRINUSE: address already in use

EADDRINUSE.sh

⇒  npm start
> [email protected] start /Users/admin/Code/WorkSpace/react-app-es6-jest
> concurrently "npm run start:server" "npm run start:client"

[0] 
[0] > [email protected] start:server /Users/admin/Code/WorkSpace/react-app-es6-jest
[0] > nodemon src/server/index.js --watch src/server -e js --exec babel-node
[0] 
[0] [nodemon] 2.0.1
[0] [nodemon] to restart at any time, enter `rs`
[0] [nodemon] watching dir(s): src/server/**/*
[0] [nodemon] watching extensions: js
[0] [nodemon] starting `babel-node src/server/index.js`
[0] events.js:174
[0]       throw er; // Unhandled 'error' event
[0]       ^
[0] 
[0] Error: listen EADDRINUSE: address already in use :::3000
[0]     at Server.setupListenHandle [as _listen2] (net.js:1279:14)
[0]     at listenInCluster (net.js:1327:12)
[0]     at Server.listen (net.js:1414:7)
[0]     at Function.listen (/Users/admin/Code/WorkSpace/react-app-es6-jest/node_modules/express/lib/application.js:618:24)
[0] [nodemon] app crashed - waiting for file changes before starting...