ECONNREFUSED on running localhost server from NodeJS

I have a NodeJS server up and running on my local machine that is listening to port 50000. From another server, that is also running on my local machine, I need to make a simple GET request to that server, but all I get is an ECONNREFUSED error:

{ Error: connect ECONNREFUSED 127.0.0.1:50000
    at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1106:14)
  errno: 'ECONNREFUSED',
  code: 'ECONNREFUSED',
  syscall: 'connect',
  address: '127.0.0.1',
  port: 50000 }

My request looks as follows, using request:

var options = {
    url: "http://localhost:50000",
    method: "GET"
}
request(options, function(error, response, body) {
    if (error) {
        console.log("[" + getDateTime() + "] Error connecting to localhost:");
        console.log(error);
        return;
   }
   // continue ...

I know that the server is up and running and that the endpoint is defined, because I can do the request to that exact same url in postman or in my browser and get a response, but somehow not in my NodeJS code.

Anybody have an idea?

Copyright Notice：Content Author:「Guest9875」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/57691836/econnrefused-on-running-localhost-server-from-nodejs