"Port 4200 is already in use. Use '--port' to specify a different port."

Hey i am runnning an angular2 app with express as backend. Getting the following issue:

[3] Port 4200 is already in use. Use '--port' to specify a different port.
[3] [nodemon] app crashed - waiting for file changes before starting...
[1] [HPM] Error occurred while trying to proxy request /api/jobs from localhost:4200 to http://localhost:3000 (ECONNREFUSED) (https://nodejs.org/api/errors.html#errors_common_system_errors)


server.js:

import * as bodyParser from 'body-parser';
import * as dotenv from 'dotenv';
import * as express from 'express';
import * as morgan from 'morgan';
import * as mongoose from 'mongoose';
import * as path from 'path';

import setRoutes from './routes';

const app = express();
dotenv.load({path: '.env'});
app.set('port', (process.env.PORT || 3000));

app.use('/', express.static(path.join(__dirname, '../')));

app.use(bodyParser.json());
app.use(bodyParser.urlencoded({extended: false}));

app.use(morgan('dev'));

mongoose.connect(process.env.MONGODB_URI);
const db = mongoose.connection;
(<any>mongoose).Promise = global.Promise;

db.on('error', console.error.bind(console, 'connection error:'));
db.on('open', () => {
console.log('Connected to MongoDB');
setRoutes(app);

app.get('/*', function (req, res) {
res.sendFile(path.join(__dirname, '../index.html'));
});

app.listen(app.get('port'), () => {
console.log('Angular 2 Full Stack listening on port ' +
app.get('port'));
});
});

export {app};


edit: Here the hole code. I think i dont reach the line with db.on('open')

when i inspect the port:



I using concurrently: with this options

"dev": "concurrently \"mongod\" \"ng serve -pc proxy.conf.json --open\" \"tsc -w -p server\" \"nodemon dist/server/server.js\"",

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