Socket.io: The value of the 'Access-Control-Allow-Origin' header in the response must not be the wildcard '*' when the request's credentials mode is 'include'. Origin 'http://localhost:3000' is therefore not allowed access. The credentials mode of requests initiated by the XMLHttpRequest is controlled by the withCredentials attribute.

Created on 3 Sep 2018 · 3Comments · Source: socketio/socket.io

Hello all,
I'm new to socket.io. I have following code in my NodeJs/Express server

const http = require('http');
const socketIo = require('socket.io');
const app = express();
const server = http.createServer(app);
const io = socketIo(server);

io.on('connection', socket => {
  console.log('New client connected');
  socket.on('disconnect', () => console.log('Client disconnected'));
  socket.emit('FromAPI', 'hello');
});
//My port here is 8848
app.listen(app.get('port'), () => {
  logger.log('info', `Server started at :${app.get('port')}`);
});

And following code in Client React app and my react app is hosted in port 3000 as http://localhost:3000

import socketIO from 'socket.io-client';
componentDidMount() {
    const endPoint = 'http://127.0.0.1:8848';
    const socket = socketIO(endPoint);
    socket.on('FromAPI', data => console.log(data));

  }

With this code i got the following error on the browser console:
polling-xhr.js:263 GET http://127.0.0.1:8848/socket.io/?EIO=3&transport=polling&t=MMT-4kl 405 (Method Not Allowed)
Failed to load http://127.0.0.1:8848/socket.io/?EIO=3&transport=polling&t=MMT-Aso: The value of the 'Access-Control-Allow-Origin' header in the response must not be the wildcard '*' when the request's credentials mode is 'include'. Origin 'http://localhost:3000' is therefore not allowed access. The credentials mode of requests initiated by the XMLHttpRequest is controlled by the withCredentials attribute.

Anyone please help me with this problem.

Source