Solving a Proxy Error (Node.js server)

Basically I get a 502 Proxy Error when running my node.js app.

Proxy Error

The proxy server received an invalid response from an upstream server.

The proxy server could not handle the request GET /play.

Reason: Error reading from remote server

My server looks like this.

var express = require('express');
var https = require('https');
var http = require('http');
var path = require('path');
var fs = require('fs');
var mysql = require('mysql');

var app = express();

var options = {
    key: fs.readFileSync('sslcert/keyfile.key', 'utf8'),
    cert: fs.readFileSync('sslcert/crtfile.crt', 'utf8')
};

var httpsServer = https.createServer(options, app);

// stuff

httpsServer.listen(process.env.PORT);

I am really sorry if this is a noob question, actually I am still a beginner in things related to node.js. Thank you for your help!

Noël.

via Noël Nadal