Latest version of socket io nodejs is not connecting to flutter applications

Question

Currently, I am trying to use sockets with flutter application which works fine when I use version ^2.3.0. But when I tried using the latest version of socket io in nodejs i.e. 4.1.2, it didn't while it's still working with a browser. I am unable to figure out what's happening.

I am sharing the code for the flutter socket io connection as well as the nodejs application.

import 'package:getparked/Utils/DomainUtils.dart';
import 'package:socket_io_client/socket_io_client.dart' as IO;

class SocketUtils {
  IO.Socket socketIO;

  IO.Socket init(onSocketConnected, onSocketDisconnected) {
    socketIO = IO.io(domainName, <String, dynamic>{
      'transports': ['websocket'],
      'upgrade': false
    });

    socketIO.connect();
    socketIO.on("connect", (data) {
      print("Connection Successfully Established...");
      onSocketConnected(socketIO);
    });

    socketIO.on("reconnect", (data) {
      print("Socket Connected Again.. Reconnection");
    });

    socketIO.on("disconnect", (data) {
      print("Socket Disconnected Unexpectedly..");
      onSocketDisconnected(socketIO);
    });

    return socketIO;
  }
}

Node js Code

const express = require('express');
const app = express();
const server=require('http').createServer(app);
io = require('socket.io')(server, {
  cors:{
      origin:"*"
  },
});
io.on('connection', (socket) => { 
  console.log(socket.id);
});
server.listen(+port, () => {
  console.log("Server is running...");
  console.log(name + " " + port);
  vehicleUtils.init();
  adminUtils.init();
});

I anyone knows any way to fix this either in flutter or nodejs without downgrading the version please let me know.

Answer 1

First of all, found the exact solution a few days after I posted it here. The problem is not with the backend or nodejs though it looks like a problem of the backend it isn't.

I was using this exact version of the socket io client which is not suitable for the later versions of socket io in nodejs for connections.

Then I came to know about this which I found in the documentation of the socket io client in the pub. dev.

Then I just changed the version rebuilt it and it worked. Try changing the version of the socket io client in your Flutter app to 2.0 which will definitely solve your problem.