How to fix Error: listen EADDRINUSE while using NodeJS?

If I run a server with the port 80, and I try to use XMLHttpRequest I am getting this error: Error: listen EADDRINUSE

Why is it problem for NodeJS, if I want to do a request, while I run a server on the port 80? For the webbrowsers it is not a problem: I can surf on the internet, while the server is running.

The server is:

  net.createServer(function (socket) {
    socket.name = socket.remoteAddress + ":" + socket.remotePort;
    console.log('connection request from: ' + socket.remoteAddress);
    socket.destroy();
  }).listen(options.port);

And the request:

var xhr = new XMLHttpRequest();

xhr.onreadystatechange = function() {
    sys.puts("State: " + this.readyState);

    if (this.readyState == 4) {
        sys.puts("Complete.\nBody length: " + this.responseText.length);
        sys.puts("Body:\n" + this.responseText);
    }
};

xhr.open("GET", "http://mywebsite.com");
xhr.send();

What really helped for me was:

killall -9 node

But this will kill a system process.

With

ps ax

you can check if it worked.

EADDRINUSE means that the port number which listen() tries to bind the server to is already in use.

So, in your case, there must be running a server on port 80 already.

If you have another webserver running on this port you have to put node.js behind that server and proxy it through it.

You should check for the listening event like this, to see if the server is really listening:

var http=require('http');

var server=http.createServer(function(req,res){
    res.end('test');
});

server.on('listening',function(){
    console.log('ok, server is running');
});

server.listen(80);

The aforementioned killall -9 node, suggested by Patrick works as expected and solves the problem but you may want to read the edit part of this very answer about why kill -9 may not be the best way to do it.

On top of that you might want to target a single process rather than blindly killing all active processes.

In that case, first get the process ID (PID) of the process running on that port (say 8888):

lsof -i tcp:8888

This will return something like:

COMMAND   PID    USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
node     57385   You   11u  IPv6 0xac745b2749fd2be3      0t0  TCP *:ddi-tcp-1 (LISTEN)

Then just do (ps - actually do not. Please keep reading below):

kill -9 57385

You can read a bit more about this here.

EDIT: I was reading on a fairly related topic today and stumbled upon this interesting thread on why should i not kill -9 a process.

Generally, you should use kill -15 before kill -9 to give the target process a chance to clean up after itself. (Processes can't catch or ignore SIGKILL, but they can and often do catch SIGTERM.) If you don't give the process a chance to finish what it's doing and clean up, it may leave corrupted files (or other state) around that it won't be able to understand once restarted.

So, as stated you should better kill the above process with:

kill -15 57385

EDIT 2: As noted in a comment around here many times this error is a consequence of not exiting a process gracefully. That means, a lot of people exit a node command (or any other) using CTRL+Z. The correct way of stopping a running process is issuing the CTRL+C command which performs a clean exit.

Exiting a process the right way will free up that port while shutting down. This will allow you to restart the process without going through the trouble of killing it yourself before being able to re-run it again.

Just a head's up, Skype will sometimes listen on port 80 and therefore cause this error if you try to listen on port 80 from Node.js or any other app.

You can turn off that behaviour in Skype by accessing the options and clicking Advanced -> Connection -> Use port 80 (Untick this)

P.S. After making that change, don't forget to restart Skype!