Socket.io опрос 404 не найден

Question

Я использую socket.io с nextjs.Я подготовил все соответствующим образом, как указано на странице nextjs github https://github.com/zeit/next.js/tree/canary/examples/with-socket.io

Но ошибка, которую я не могу найти, это 'GET http://localhost:3000/socket.io/?EIO=3&transport=polling&t=Mt-iX4s 404 (Not Found) polling error' polling-xhr.js:267

Мой код для server.js -

    const express = require('express')
const socketApp = require('express')()
const server = require('http').Server(socketApp)
const io = require('socket.io')(server)

const next = require('next')

const glob = require('glob')
const bodyParser = require('body-parser')
const port = parseInt(process.env.PORT, 10) || 3000
const dev = process.env.NODE_ENV !== 'production'
const app = next({ dev })
const handle = app.getRequestHandler()
const mongoose = require('mongoose')

// import routes
const routes = require('./routes')
const routerhandler = routes.getRequestHandler( app )



/*
-------------- Mongo db connection -----------
*/
const DB = require('./db')

DB.on( 'error', () => {
    console.log('Error Happened')
} )
DB.once( 'open', () => {
    console.log('Database connected')
} )


// Socket.io
io.on('connection', socket => {
    console.log('Connected to websocket!')
})

const userRoutes = require('./api/userRoutes')
/*
------------------------ Mongo db connection ends ------------------------
*/
app.prepare().then(() => {
    const server = express()

    // Parse application/x-www-form-urlencoded
    server.use(bodyParser.urlencoded({ extended: false }))
    // Parse application/json
    server.use(bodyParser.json())

    // Allows for cross origin domain request:
    server.use(function(req, res, next) {
        res.header("Access-Control-Allow-Origin", "*")
        res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept")
        next()
    })
    // Express-mongo API routes
    server.use('/api/users', userRoutes)
    // Next Routes
    server.get('*', routerhandler)
    server.listen(port, err => {
        if (err) throw err
        console.log(`> Ready on http://localhost:${port}`)
    })

})

// middleware that is specific to this router

в вышеупомянутом файле server.js, я подготовил соединение socket.io с сервером и конфигурацию mongoDB

также мой_app.js file

    import React from 'react'
import { Provider } from 'react-redux'
import nextCookie from 'next-cookies'
import fetch from 'isomorphic-unfetch'

import io from 'socket.io-client'

import './style.sass'

import App, { Container } from 'next/app'
import withRedux from 'next-redux-wrapper'
import withReduxSaga from 'next-redux-saga'
import configureStore from '../store'

class MyApp extends App{
    static async getInitialProps({Component, ctx}) {
        const {cryptotoken} = nextCookie(ctx)
        const protocol = process.env.NODE_ENV === 'production' ? 'https' : 'http'

        const apiUrl = process.browser
            ? `${protocol}://${window.location.host}/api/users/profile`
            : `${protocol}://${ctx.req.headers.host}/api/users/profile`

        const redirectOnError = () =>
            process.browser
                ? Router.push('/signin')
                : ctx.res.writeHead(301, { Location: '/signin' })

        const res = await fetch(apiUrl, {
            credentials: 'include',
            headers: {
                'Content-Type': 'application/json',
                Authorization: 'Bearer ' + cryptotoken
            }
        });
        const data = await res.json()
        if(data.user){
            ctx.store.dispatch({type: 'USER_LOGGEDIN',  payload: data.loggedin})
            ctx.store.dispatch({type: 'USER_EMAIL',     payload: data.user.email})
            ctx.store.dispatch({type: 'USER_NAME',      payload: data.user.username})
            ctx.store.dispatch({type: 'USER_ID',        payload: data.user._id})
            ctx.store.dispatch({type: 'EXCHANGE_BUY',   payload: data.user.tradings.buy.data})
        }
        const pageProps = Component.getInitialProps ? await Component.getInitialProps(ctx) : {}

        return {pageProps};
    }
    state = {
        socket: null
    }
    componentDidMount () {
        // connect to WS server and listen event
        const socket = io()
        socket.on('connection', ()=>{
            console.log('connected to socket client')
        })
            this.setState({ socket })
    }

    // close socket connection
    componentWillUnmount () {
        this.state.socket.close()
    }
    render(){
        const { Component, pageProps, store } = this.props
        return(
                <Container>
                    <Provider store={store}>
                        <Component {...pageProps}  socket={this.state.socket} />
                    </Provider>
                </Container>
            )
    }
}
export default withRedux(configureStore)(withReduxSaga(MyApp))

Все хорошо, но в итоге я получаю эту ошибку в консоли. Могу ли я решить это?