Socket.IO failed: Error during WebSocket handshake: Unexpected response code: 400

Question

I have a socket.io app hosted in A2Hosting shared hosting and the problem is that it uses only xhr polling because there seems to be an error establishing socket handshake.

This is the error I'm receiving:

index.js:83 WebSocket connection to 'wss://www.xxxxxxx.com/socket.io/? 
EIO=3&transport=websocket&sid=7KqOx4VgE6xd507zAACf' failed: Error 
during WebSocket handshake: Unexpected response code: 400

app.js

var app = require('express')();
var server = require('http').Server(app);
var io = require('socket.io')(server);
const port = 65533

app.use(function(req, res, next) {
res.setHeader("Access-Control-Allow-Origin", 
"https://www.xxxxx.com/xxxx/xxxx");
res.setHeader("Access-Control-Allow-Credentials", true);
next();
});

server.listen(port, () => console.log(`Example app listening on port 
${port}!`));

app.get('/', (req, res) => res.send('Socket is running....'))

// io.set('transports', ['websocket']);

io.on('connection', function (socket) {
  socket.on('scan_complete', function (data) {
  io.emit("scan_result", data);
console.log(data);
});
});

.htaccess for app.js

RewriteEngine On
RewriteRule ^$ http://127.0.0.1:65533/ [P,L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ http://127.0.0.1:65533/$1 [P,L]

client side

$(function () {
        var socket = io.connect("https://www.xxxxx.com/");

        socket.on('scan_result', function (msg) {
            $('#content').html(profile);
        })

    })

Answer 1

This works for me:

    const io = require('socket.io')(server, {
      serveClient: false,
      // below are engine.IO options
      origins: '*:*',
      transports: ['polling'],  <== this is what solved my problem
      pingInterval: 10000,
      pingTimeout: 5000,
      cookie: false
    });

    io.on('connection', socket => {
      console.log('IO Connected!', socket.id);

      ...

      socket.on('disconnect', () => {
        console.log('User disconnected!', socket.id);
      });
    });