Получение ошибки DeprecationWarning при создании API

Я изучаю rest api, но продолжаю получать следующую ошибку. Почему? Я использую Node JS, Mongo DB и Express. Я новичок в этом.

Код:

var express = require('express');
var app = express();
var bodyParser = require('body-parser');
var mongoose = require('mongoose');

//connect to mongoose
mongoose.connect('mongodb://localost/bookstore');
var db = mongoose.connection;

app.get('/', function(req, res){
    res.send('Please use /api for the API.');
});

app.listen(3000);
console.info('Running on port 3000...');

Ошибка:

(node:7908) DeprecationWarning: current URL string parser is deprecated, and wil
l be removed in a future version. To use the new parser, pass option { useNewUrl
Parser: true } to MongoClient.connect.
events.js:183
      throw er; // Unhandled 'error' event
      ^

Error: listen EADDRINUSE :::3000
    at Server.setupListenHandle [as _listen2] (net.js:1360:14)
    at listenInCluster (net.js:1401:12)
    at Server.listen (net.js:1485:7)
    at Function.listen (C:\apiproject\bookstore\node_modules\express\lib\applica
tion.js:618:24)
    at Object.<anonymous> (C:\apiproject\bookstore\app.js:14:5)
    at Module._compile (module.js:653:30)
    at Object.Module._extensions..js (module.js:664:10)
    at Module.load (module.js:566:32)
    at tryModuleLoad (module.js:506:12)
    at Function.Module._load (module.js:498:3)
    at Function.Module.runMain (module.js:694:10)
    at startup (bootstrap_node.js:204:16)
    at bootstrap_node.js:625:3