未找到状态：404

Question

const express = require("express"),
    http = require("http"),
    bodyParser = require("body-parser"),
    cookieParser = require('cookie-parser'),
    session = require('express-session'),
    morgan = require('morgan'),
    methodOverride = require('method-override'),
    compression = require('compression');

const app = express();
// compress responses
app.use(compression());

process.on('uncaughtException', function(exception) {
    console.log(exception);
});

const config = require("./app/config.js")();
const logger = require("./app/server/modules/logger");

//app Config.
app.use(methodOverride());
app.set('env', 'dev');
app.use(morgan('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ // to support URL-encoded bodies
    extended: true
}));

//cross domain 
app.use(function(req, res, next) {
    if (req.method === 'OPTIONS') {
        var headers = {};
        headers["Access-Control-Allow-Origin"] = "*";
        headers["Access-Control-Allow-Methods"] = "POST, GET, PUT, DELETE, OPTIONS";
        headers["Access-Control-Allow-Credentials"] = false;
        headers["Access-Control-Max-Age"] = '86400'; // 24 hours
        headers["Access-Control-Allow-Headers"] = "X-Requested-With, X-HTTP-Method-Override, Content-Type, Accept";
        res.writeHead(200, headers);
        res.end();
    }
    res.header("Access-Control-Allow-Origin", "*");
    res.header("Access-Control-Allow-Methods", "POST, GET, PUT, DELETE, OPTIONS");
    res.header["Access-Control-Allow-Credentials"] = false;
    res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With,X-HTTP-Method-Override, Content-Type, Accept");
    next();
});

app.use(cookieParser());
app.use(session({ secret: 'xxxxxxxxxxx' }));
// app.use(cookieParser('optional secret string'));
// app.use(session({secret: 'xxxxxxxxxxx'}));
app.locals.pretty = true;

//Folder config.
/*app.use(express.static(__dirname + '/app/user/'));*/
app.use('/', express.static(__dirname + '/app/user/'));
app.use('/admin', express.static(__dirname + '/app/admin/'));

require('./app/server/router')(app); //route file

// catch 404 and forward to error handler
app.use(function(req, res, next) {
    const err = new Error('Not Found');
    err.status = 404;
    next(err);
});

if (app.get('env') === 'dev') {

    app.use(function(err, req, res, next) {
        res.status(err.status || 500);
        res.json({
            message: err.message,
            error: err
        });
    });

}

// production error handler
// no stacktraces leaked to user
app.use(function(err, req, res, next) {
    res.status(err.status || 500);
    res.render('error.html', {
        message: err.message,
        error: {}
    });
});

http.createServer(app).listen(config.port, function(err) {
    if (err) console.log(err);
    logger.info("server listening on port " + config.port + " in " +
        config.mode + " mode");
});

这是我的http链接http://localhost:9989/，稍后它将重新定向到http://localhost:9989/login，这是第一次正常工作，当我刷新http://localhost:9989/login时，它会显示{“message”：“Not Found” ，“错误”：{“状态”：404}}，为什么会发生？这有什么解决方案吗？或者我有任何错误吗？请指导我!!