Receiving net::ERR_EMPTY_RESPONSE with Nodejs Post Request

I'm trying to make a post request in my Node app; however, I am getting the following error.

OPTIONS http://localhost:27017/postDebate net::ERR_EMPTY_RESPONSE

How to resolve this?

Here is my route:

var express = require('express');
var router = express.Router();
var Debate = require('../models/debate');
var mdb = require('mongodb').MongoClient,
  ObjectId = require('mongodb').ObjectID,
  assert = require('assert');
var api_version = '1';
var url = 'mongodb://localhost:27017/debate';

router.post('/'+api_version+'/postDebate', function(req, res, next) {
  var debate = new Debate(req.body);
  console.log(debate, "here is the debate");
  debate.save(function(err) {
    if (err) throw err;
    console.log('Debate saved successfully!');
  });
  res.json(debate);
});

module.exports = router;

And since I am invoking this route after onclick calling a function in my ejs file, here is my javascript file.

function postDebate() {
  var topic = document.getElementById('topic').value;
  var tags = document.getElementById('tags').value;
  var argument = document.getElementById('argument').value;

  var debateObject = {
    "topic": topic,
    "tags": tags,
    "argument": argument
  };
  console.log(topic, tags, argument);

  $.ajax({
    type: 'POST',
    data: JSON.stringify(debateObject),
    contentType: "application/json",
        //contentType: "application/x-www-form-urlencoded",
        dataType:'json',
        url: 'http://localhost:27017/post',                      
        success: function(data) {
          console.log(JSON.stringify(data), "This is the debateObject");                               
        },
        error: function(error) {
          console.log(error);
        }
      });
}

How do I resolve this error? What is the problem here?

OPTIONS http://localhost:27017/postDebate net::ERR_EMPTY_RESPONSE

via Rohit Tigga