title: UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): MongoError: failed to connect to server on first connect
body: <p>I have an app developed using MEAN stack. I am getting the following error</p>
  
  <p><strong><em>(node:4920) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): MongoError: failed to connect to server [ds047865.mongolab.com:47865] on first connect [Mon
  goError: connect ECONNREFUSED 130.211.211.211:47865]</em></strong></p>
  
  <p><strong><em>(node:4920) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a
  non-zero exit code</em></strong></p>
  
  <p>here is my code:</p>
  
  <pre><code>    var mongoose = require('mongoose');
  var validator = require('mongoose-unique-validator'); 
  var nodemailer = require('nodemailer');
  mongoose.connect('mongodb://naresh:naresh@ds249025.mlab.com:49025/languageapp', { useMongoClient: true });  
  var db = mongoose.connection;
  db.on('connect', function () { console.log('connected'); });
  
  
  var userSchema = new mongoose.Schema({
      userName: { type: String, required: true, index: true, unique: true },
      userEmail: { type: String, required: true, index: true, unique: true },
      userPass: { type: String, required: true },
      Date: { type: String, default: Date.now() },
      userResult: String
  });
  var questionSchema = new mongoose.Schema({
      question: { type: String, unique: true },
      op1: String,
      op2: String,
      op3: String,
      op4: String,
      rightAnswer: String,
      questionType: String,
      questionID: String,
      quizTopic: String,
      CreatedAt: { type: String, default: Date.now() }
  });
  var resultSchema = new mongoose.Schema({
      userID: String,
      userName: String,
      userMatriculation: String,
      userEmail: String,
      quizTopic: String,
      userResult: String,
      date: { type: String, default: Date.now() }
  });
  userSchema.plugin(validator);
  var User = mongoose.model('Users', userSchema);
  var Question = mongoose.model('Questions', questionSchema);
  var Result = mongoose.model('Results', resultSchema);
  </code></pre>
  
  <p>I am not using any promises though am getting these errors.</p>