Develop Reference

Localhost:3000 is not working properly in windows while creating a reactjs app with CRA

There are few points, for the past few days I am trying to figure out the issue but I am stuck.
I have tried to stop localhost:3000 with
netstat -ano | findstr :3000
taskkill /PID myPIDhere /F
But still, then I am getting-
TCP 0.0.0.0:3000 0.0.0.0:0 LISTENING 5748
and it says - ERROR: The process with PID 5748 could not be terminated.
Reason: There is no running instance of the task.
And still, when I visit localhost:3000 it trying to load again and again.
whenever I try to create a reactjs app with CRA.. the terminal hangs there forever.
same goes for NPM install in a creatjs app.

EDIT 2 : netstat -ano | findstr :3000
tskill typeyourPIDhere
Use tskill in windows cmd vs taskkill on git-bash
EDIT: Try wmic process where name="[process name]" call terminate / delete
Off the top of my head, try changing CRA port to something else?
https://scriptverse.academy/tutorials/reactjs-change-port-number.html
Try one of these methods, and see if they help you at least run CRA.

EADDRINUSE exception with node server [duplicate]

I have a simple server running in node.js using connect:
var server = require('connect').createServer();
//actions...
server.listen(3000);
In my code I have actual handlers, but thats the basic idea. The problem I keep getting is
EADDRINUSE, Address already in use
I receive this error when running my application again after it previously crashed or errors. Since I am not opening a new instance of terminal I close out the process with ctr + z.
I am fairly certain all I have to do is close out the server or connection. I tried calling server.close() in process.on('exit', ...); with no luck.

First, you would want to know which process is using port 3000
sudo lsof -i :3000
this will list all PID listening on this port, once you have the PID you can terminate it with the following:
kill -9 <PID>
where you replace <PID> by the process ID, or the list of process IDs, the previous command output.

You can also go the command line route:
ps aux | grep node
to get the process ids.
Then:
kill -9 PID
Doing the -9 on kill sends a SIGKILL (instead of a SIGTERM).
SIGTERM has been ignored by node for me sometimes.

I hit this on my laptop running win8. this worked.
Run cmd.exe as 'Administrator':
C:\Windows\System32>taskkill /F /IM node.exe
SUCCESS: The process "node.exe" with PID 11008 has been terminated.

process.on('exit', ..) isn't called if the process crashes or is killed. It is only called when the event loop ends, and since server.close() sort of ends the event loop (it still has to wait for currently running stacks here and there) it makes no sense to put that inside the exit event...
On crash, do process.on('uncaughtException', ..) and on kill do process.on('SIGTERM', ..)
That being said, SIGTERM (default kill signal) lets the app clean up, while SIGKILL (immediate termination) won't let the app do anything.

Check the PID i.e. id of process running on port 3000 with below command :
lsof -i tcp:3000
It would output something like following:
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
node 5805 xyz 12u IPv6 63135 0t0 TCP *:3000 (LISTEN)
Now kill the process using :
kill -9 5805

For macOS Monterey(12.0):
Apple introduced some changes for AirPlay on macOS Monterey. Now, it uses 5000 and 7000 ports. If you are using these ports in your project, you need to disable this feature.
System Preferences > Sharing > untick AirPlay Receiver
For macOS Ventura(13.0) and above users:
System Settings > General > disable AirPlay Receiver

I found this solution, try it
Give permission use sudo
sudo pkill node

I usually use
npx kill-port 3000
or on my mac.
killall node

Rewriting #Gerard 's comment in my answer:
Try pkill nodejs or pkill node if on UNIX-like OS.
This will kill the process running the node server running on any port.
Worked for me.

Linux
Run ps and determine the PID of your node process.
Then, run sudo kill PID
Windows
Use tasklist to display the list of running processes:
tasklist /O
Then, kill the node process like so (using the PID obtained from the tasklist command):
taskkill /pid PID

Here is a one liner (replace 3000 with a port or a config variable):
kill $(lsof -t -i:3000)

For windows open Task Manager and find node.exe processes. Kill all of them with End Task.

I was getting this error once and took many of the approaches here.
My issues was that I had two app.listen(3000); calls in the same app.js script. The first app.listen() succeeded where the second threw the error.
Another useful command I came across that helped me debug was sudo fuser -k 3000/tcp which will kill any rogue processes you might have started (some processes may restart, e.g. if run with forever.js, but it was useful for me).

For Visual Studio Noobs like me
You may be running the process in other terminals!
After closing the terminal in Visual Studio, the terminal just disappears.
I manually created a new one thinking that the previous one was destroyed. In reality, every time I was clicking on New Terminal I was actually creating a new one on top of the previous ones.
So I located the first terminal and... Voila, I was running the server there.

Windows by Cmd
1/2. search => write cmd => open node.js command prompt
2/2. Run windows command: taskkill
Ends one or more tasks or processes.
taskkill /f /im node.exe
/f - force ended
/im - Specifies the image name of the process to be terminated.
node.exe - executable file
Windows - Mannualy by Task Manager
This command is the same as going to Task Manager under the details tab & select node tasks (Tidy in my opinion).
And end task
Visual studio
Sometimes there is more than one terminal/task (client/server and so on).
Select and close by ctrl + c.

You may run into scenarios where even killing the thread or process won't actually terminate the app (this happens for me on Linux and Windows every once in a while). Sometimes you might already have an instance running that you didn't close.
As a result of those kinds of circumstances, I prefer to add to my package.json:
"scripts": {
"stop-win": "Taskkill /IM node.exe /F",
"stop-linux": "killall node"
},
I can then call them using:
npm run stop-win
npm run stop-Linux
You can get fancier and make those BIN commands with an argument flag if you want. You can also add those as commands to be executed within a try-catch clause.

FYI, you can kill the process in one command sudo fuser -k 3000/tcp. This can be done for all other ports like 8000, 8080 or 9000 which are commonly used for development.

ps aux | grep node
kill -9 [PID] (provided by above command)
Description:
ps will give the process status, aux provide the list of a: all users processes, u: user own processes, x: all other processes not attached to terminal.
pipe symbol: | will pass the result of ps aux to manipulate further.
grep will search the string provided(node in our case) from the list provided by ps aux.

First find out what is running using:
sudo lsof -nP -i4TCP:3000 | grep LISTEN
You will get something like:
php-fpm 110 root 6u IPv4 0x110e2ba1cc64b26d 0t0 TCP 127.0.0.1:3000 (LISTEN)
php-fpm 274 _www 0u IPv4 0x110e2ba1cc64b26d 0t0 TCP 127.0.0.1:3000 (LISTEN)
php-fpm 275 _www 0u IPv4 0x110e2ba1cc64b26d 0t0 TCP 127.0.0.1:3000 (LISTEN)
Then you can kill the process as followed:
sudo kill 110
Then you will be able to run without getting the listen EADDRINUSE :::3000 errors

Really simply for all OS's ..
npx kill-port 3000
Although your problem is as mentioned above you need to catch the different ways node can exit for example
process.on('uncaughtException', (err, origin) => {
console.log(err);
});
// insert other handlers.

bash$ sudo netstat -ltnp | grep -w ':3000'
- tcp6 0 0 :::4000 :::* LISTEN 31157/node
bash$ kill 31157

PowerShell users:
Taskkill /IM node.exe /F

UI solution For Windows users: I found that the top answers did not work for me, they seemed to be commands for Mac or Linux users. I found a simple solution that didn't require any commands to remember: open Task Manager (ctrl+shift+esc). Look at background processes running. Find anything Node.js and end the task.
After I did this the issue went away for me. As stated in other answers it's background processes that are still running because an error was previously encountered and the regular exit/clean up functions didn't get called, so one way to kill them is to find the process in Task Manager and kill it there. If you ran the process from a terminal/powerShell you can usually use ctrl+c to kill it.

Task Manager (ctrl+alt+del) ->
Processes tab ->
select the "node.exe" process and hit "End Process"

Just in case check if you have added this line multiple times by mistake
app.listen(3000, function() {
console.log('listening on 3000')
});
The above code is for express but just check if you are trying to use the same port twice in your code.

In windows users: open task manager and end task the nodejs.exe file, It works fine.

On Windows, I was getting the following error:
EADDRINUSE: address already in use :::8081.
Followed these steps:
Opened CMD as Admin
Ran the folowing
command netstat -ano|findstr "PID :8081"
got the following processes:
killed it via:
taskkill /pid 43144 /f
On MAC you can do like this:
raghavkhunger#MacBook-Air ~ % lsof -i tcp:8081
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
node 23722 username 24u IPv6 0xeed16d7ccfdd347 0t0 TCP *:sunproxyadmin (LISTEN)
username#MacBook-Air ~ % kill -9 23722

With due respect to all the answers in the form, I would like to add a point.
I found that when I terminate a node app on error using Ctrl + Z, the very next time when I try to open it got the same error EADDRINUSE.
When I use Ctrl + C to terminate a node app, the next time I opened it, it did without a hitch.
Changing the port number to something other than the one in error solved the issue.

using netstat to get all node processes with the port they are using and then kill the only one you want by PID
netstat -lntp | grep node
you will get all node processes
tcp6 0 0 :::5744 :::* LISTEN 3864/node
and then when you get the PID (3864) just kill the processes by PID
kill -HUP PID

You may use hot-node to prevent your server from crashing/ run-time-errors. Hot-node automatically restarts the nodejs application for you whenever there is a change in the node program[source] / process[running node program].
Install hot-node using npm using the global option:
npm install -g hotnode

Why do I keep getting a throw er on my ternimal [duplicate]

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!

You should try killing the process that is listening on port 80.
Killall will kill all the node apps running. You might not want to do that. With this command you can kill only the one app that is listening on a known port.
If using unix try this command:
sudo fuser -k 80/tcp

Error reason: You are trying to use the busy port number
Two possible solutions for Windows/Mac
Free currently used port number
Select another port number for your current program
1. Free Port Number
Windows
1. netstat -ano | findstr :4200
2. taskkill /PID 5824 /F
Mac
You can try netstat
netstat -vanp tcp | grep 3000
For OSX El Capitan and newer (or if your netstat doesn't support -p), use lsof
sudo lsof -i tcp:3000
if this does not resolve your problem, Mac users can refer to complete discussion about this issue Find (and kill) process locking port 3000 on Mac
2. Change Port Number?
Windows
set PORT=5000
Mac
export PORT=5000

Under a controller env, you could use:
pkill node before running your script should do the job.
Bear in mind this command will kill all the node processes, which might be right if you have i.e a container running only one instance, our you have such env where you can guarantee that.
In any other scenario, I recommend using a command to kill a certain process id or name you found by looking for it programmatically. like if your process is called, node-server-1 you could do pkill node-server-1.
This resource might be useful to understand:
https://www.thegeekstuff.com/2009/12/4-ways-to-kill-a-process-kill-killall-pkill-xkill/

lsof -i:3000;
kill -9 $(lsof -t -i:3000);
// 3000 is a your port
// This "lsof -i:3000;" command will show PID
kill PID
ex: kill 129393

Another thing that can give this error, is two HTTP servers in the same node code. I was updating some Express 2 to Express 3 code, and had this...
http.createServer(app).listen(app.get('port'), function(){
console.log('Express server listening on port ' + app.get('port'));
});
// tons of shit.
http.createServer(app).listen(app.get('port'), function(){
console.log('Express server listening on port ' + app.get('port'));
});
And, it triggered this error.

Your application is already running on that port 8080 .
Use this code to kill the port and run your code again
sudo lsof -t -i tcp:8080 | xargs kill -9

This works for me (I'm using mac). Run this command
lsof -PiTCP -sTCP:LISTEN
This's going to display a list of ports that your syetem is using. Find the PID that your node is running
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
node 17269 hientrq 16u IPv6 0xc42959c6fa30c3b9 0t0 TCP *:51524 (LISTEN)
node 17269 hientrq 19u IPv4 0xc42959c71ae86fc1 0t0 TCP localhost:1337 (LISTEN)
and run kill -9 [YOUR_PID]

EADDRINUSE means that the port(which we try to listen in node application) is already being used. In order to overcome, we need to identify which process is running with that port.
For example if we are trying to listen our node application in 3000 port. We need to check whether that port is already is being used by any other process.
step1:
$sudo netstat -plunt |grep :3000
That the above command gives below result.
tcp6 0 0 :::3000 :::* LISTEN 25315/node
step2:
Now you got process ID(25315), Kill that process.
kill -9 25315
step3:
npm run start
Note: This solution for linux users.

sudo kill $(sudo lsof -t -i:80)
for force kill
sudo kill -9 $(sudo lsof -t -i:80)
use above cmd to kill particular port and then run your server

Try both commands and it will stop all node process.
killall 9 node
pkill node
npm start

In below command replace your portNumber
sudo lsof -t -i tcp:portNumber | xargs kill -9

There is a way to terminate the process using Task Manager:
Note that this solution is for Windows only
Go to the Task Manager (or using the shortcut Ctrl + Shift + Esc)
On "Background Processes", find "Node.js" processes and terminate them (Right-click them and choose "End Task")
Now you should be able to start again

This error comes when you have any process running on a port on which you want to run your application.
how to get which process running on that port=>
command:
sudo netstat -ap | grep :3000
output : you will get the process information which is using that port
tcp 0 0 IPaddress:3000 : LISTEN 26869/node
Now you can kill that process
sudo kill -9 26869

EADDRINUSE means port of your nodejs app is already in use.
Now you have kill the process/app running on that port.
Find the process id of app by:
lsof -i tcp:3000
Now u will get process id from this.
Run this:
kill -9 processId

I got:
Error: listen EADDRINUSE: address already in use :::8000
I was trying to look for the process listening to port 8000
and had no luck - there were none (sudo netstat -nlp | grep 8000 ).
It turned out I had app.listen(8000) written twice in my script.
My assumption is that the interference was happening only in a short time when trying to run the script, so looking for processes listening to the port before and after error didn't show any.

I have seen this error before (in node) with http.client, and as I recall, the problem had to do with not initializing the httpClient or setting bad options in the httpClient creation and/or in the url request.

Error: listen EADDRINUSE means the port which you want to assign/bind to your application server is already in use. You can either assign another port to your application.
Or if you want to assign the same port to the app. Then kill the application that is running at your desired port.
For a node application what you can try is, find the process id for the node app by :
ps -aux | grep node
After getting the process id, do
kill process_id

In my case Apache HTTP Server was run on port 80 I solved it by issue the command as root
sudo killall httpd
Update
If Jenkin is installed and running on your Mac;
You can check it with sudo lsof -i tcp:8080
If Yes, and You want to stop Jenkins only once, run: sudo launchctl unload /Library/LaunchDaemons/org.jenkins-ci.plist

I have the same problem too,and I simply close the terminal and open a new terminal and run
node server.js
again. that works for me, some time just need to wait for a few second till it work again.
But this works only on a developer machine instead of a server console..

On Debian i found out to run on port 80 you need to issue the command as root i.e
sudo node app.js
I hope it helps

Two servers can not listen on same port, so check out if other server listening on same port, also check out for browser sync if its running on same port

For other people on windows 10 with node as localhost and running on a port like 3500, not 80 ...
What does not work:
killall ? command not found
ps -aux | grep 'node' ? ps: user x unknown
What shows information but still not does work:
ps -aef | grep 'node'
ps ax
kill -9 61864
What does work:
Git Bash or Powershell on Windows
net -a -o | grep 3500 (whatever port you are looking for)
Notice the PID ( far right )
I could not get killall to work... so
Open your task manager
On processes tab , right click on Name or any column and select to include PID
Sort by PID, then right click on right PID and click end task.
Now after that not so fun exercise on windows, I realized I can use task manager and find the Node engine and just end it.
FYI , I was using Visual Studio Code to run Node on port 3500, and I use Git Bash shell inside VS code. I had exited gracefully with Ctrl + C , but sometimes this does not kill it. I don't want to change my port or reboot so this worked. Hopefully it helps others. Otherwise it is documentation for myself.

For windows users execute the following command in PowerShell window to kill all the node processes.
Stop-Process -processname node

The error EADDRINUSE (Address already in use) reports that there is already another process on the local system occupying that address / port.
There is a npm package called find-process which helps finding (and closing) the occupying process.
Here is a little demo code:
const find = require('find-process')
const PORT = 80
find('port', PORT)
.then((list) => {
console.log(`Port "${PORT}" is blocked. Killing blocking applications...`)
const processIds = list.map((item) => item.pid)
processIds.forEach((pid) => process.kill(pid, 10))
})
I prepared a small sample which can reproduce the EADDRINUSE error. If you launch the following program in two separate terminals, you will see that the first terminal will start a server (on port "3000") and the second terminal will close the already running server (because it blocks the execution of the second terminal, EADDRINUSE):
Minimal Working Example:
const find = require('find-process')
const http = require('http')
const PORT = 3000
// Handling exceptions
process.on('uncaughtException', (error) => {
if (error.code === 'EADDRINUSE') {
find('port', PORT)
.then((list) => {
const blockingApplication = list[0]
if (blockingApplication) {
console.log(`Port "${PORT}" is blocked by "${blockingApplication.name}".`)
console.log('Shutting down blocking application...')
process.kill(blockingApplication.pid)
// TODO: Restart server
}
})
}
})
// Starting server
const server = http.createServer((request, response) => {
response.writeHead(200, {'Content-Type': 'text/plain'})
response.write('Hello World!')
response.end()
})
server.listen(PORT, () => console.log(`Server running on port "${PORT}"...`))

I had the same issue recently.
It means that the port is already being used by another application (express or other software)
In my case, I had accidentally run express on 2 terminals, so exiting the terminal using 'Ctrl + C' fixed things for me. (Run server from only one terminal)
Hope it helps others.

Seems there is another Node ng serve process running. Check it by typing this in your console (Linux/Mac):
ps aux|grep node
and quit it with:
kill -9 <NodeProcessId>
OR alternativley use
ng serve --port <AnotherFreePortNumber>
to serve your project on a free port of you choice.

Error: listen EADDRINUSE [duplicate]

I have a simple server running in node.js using connect:
var server = require('connect').createServer();
//actions...
server.listen(3000);
In my code I have actual handlers, but thats the basic idea. The problem I keep getting is
EADDRINUSE, Address already in use
I receive this error when running my application again after it previously crashed or errors. Since I am not opening a new instance of terminal I close out the process with ctr + z.
I am fairly certain all I have to do is close out the server or connection. I tried calling server.close() in process.on('exit', ...); with no luck.

First, you would want to know which process is using port 3000
sudo lsof -i :3000
this will list all PID listening on this port, once you have the PID you can terminate it with the following:
kill -9 <PID>
where you replace <PID> by the process ID, or the list of process IDs, the previous command output.

You can also go the command line route:
ps aux | grep node
to get the process ids.
Then:
kill -9 PID
Doing the -9 on kill sends a SIGKILL (instead of a SIGTERM).
SIGTERM has been ignored by node for me sometimes.

I hit this on my laptop running win8. this worked.
Run cmd.exe as 'Administrator':
C:\Windows\System32>taskkill /F /IM node.exe
SUCCESS: The process "node.exe" with PID 11008 has been terminated.

process.on('exit', ..) isn't called if the process crashes or is killed. It is only called when the event loop ends, and since server.close() sort of ends the event loop (it still has to wait for currently running stacks here and there) it makes no sense to put that inside the exit event...
On crash, do process.on('uncaughtException', ..) and on kill do process.on('SIGTERM', ..)
That being said, SIGTERM (default kill signal) lets the app clean up, while SIGKILL (immediate termination) won't let the app do anything.

Check the PID i.e. id of process running on port 3000 with below command :
lsof -i tcp:3000
It would output something like following:
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
node 5805 xyz 12u IPv6 63135 0t0 TCP *:3000 (LISTEN)
Now kill the process using :
kill -9 5805

For macOS Monterey(12.0):
Apple introduced some changes for AirPlay on macOS Monterey. Now, it uses 5000 and 7000 ports. If you are using these ports in your project, you need to disable this feature.
System Preferences > Sharing > untick AirPlay Receiver
For macOS Ventura(13.0) and above users:
System Settings > General > disable AirPlay Receiver

I found this solution, try it
Give permission use sudo
sudo pkill node

I usually use
npx kill-port 3000
or on my mac.
killall node

Rewriting #Gerard 's comment in my answer:
Try pkill nodejs or pkill node if on UNIX-like OS.
This will kill the process running the node server running on any port.
Worked for me.

Linux
Run ps and determine the PID of your node process.
Then, run sudo kill PID
Windows
Use tasklist to display the list of running processes:
tasklist /O
Then, kill the node process like so (using the PID obtained from the tasklist command):
taskkill /pid PID

Here is a one liner (replace 3000 with a port or a config variable):
kill $(lsof -t -i:3000)

For windows open Task Manager and find node.exe processes. Kill all of them with End Task.

I was getting this error once and took many of the approaches here.
My issues was that I had two app.listen(3000); calls in the same app.js script. The first app.listen() succeeded where the second threw the error.
Another useful command I came across that helped me debug was sudo fuser -k 3000/tcp which will kill any rogue processes you might have started (some processes may restart, e.g. if run with forever.js, but it was useful for me).

For Visual Studio Noobs like me
You may be running the process in other terminals!
After closing the terminal in Visual Studio, the terminal just disappears.
I manually created a new one thinking that the previous one was destroyed. In reality, every time I was clicking on New Terminal I was actually creating a new one on top of the previous ones.
So I located the first terminal and... Voila, I was running the server there.

Windows by Cmd
1/2. search => write cmd => open node.js command prompt
2/2. Run windows command: taskkill
Ends one or more tasks or processes.
taskkill /f /im node.exe
/f - force ended
/im - Specifies the image name of the process to be terminated.
node.exe - executable file
Windows - Mannualy by Task Manager
This command is the same as going to Task Manager under the details tab & select node tasks (Tidy in my opinion).
And end task
Visual studio
Sometimes there is more than one terminal/task (client/server and so on).
Select and close by ctrl + c.

You may run into scenarios where even killing the thread or process won't actually terminate the app (this happens for me on Linux and Windows every once in a while). Sometimes you might already have an instance running that you didn't close.
As a result of those kinds of circumstances, I prefer to add to my package.json:
"scripts": {
"stop-win": "Taskkill /IM node.exe /F",
"stop-linux": "killall node"
},
I can then call them using:
npm run stop-win
npm run stop-Linux
You can get fancier and make those BIN commands with an argument flag if you want. You can also add those as commands to be executed within a try-catch clause.

FYI, you can kill the process in one command sudo fuser -k 3000/tcp. This can be done for all other ports like 8000, 8080 or 9000 which are commonly used for development.

ps aux | grep node
kill -9 [PID] (provided by above command)
Description:
ps will give the process status, aux provide the list of a: all users processes, u: user own processes, x: all other processes not attached to terminal.
pipe symbol: | will pass the result of ps aux to manipulate further.
grep will search the string provided(node in our case) from the list provided by ps aux.

First find out what is running using:
sudo lsof -nP -i4TCP:3000 | grep LISTEN
You will get something like:
php-fpm 110 root 6u IPv4 0x110e2ba1cc64b26d 0t0 TCP 127.0.0.1:3000 (LISTEN)
php-fpm 274 _www 0u IPv4 0x110e2ba1cc64b26d 0t0 TCP 127.0.0.1:3000 (LISTEN)
php-fpm 275 _www 0u IPv4 0x110e2ba1cc64b26d 0t0 TCP 127.0.0.1:3000 (LISTEN)
Then you can kill the process as followed:
sudo kill 110
Then you will be able to run without getting the listen EADDRINUSE :::3000 errors

Really simply for all OS's ..
npx kill-port 3000
Although your problem is as mentioned above you need to catch the different ways node can exit for example
process.on('uncaughtException', (err, origin) => {
console.log(err);
});
// insert other handlers.

bash$ sudo netstat -ltnp | grep -w ':3000'
- tcp6 0 0 :::4000 :::* LISTEN 31157/node
bash$ kill 31157

PowerShell users:
Taskkill /IM node.exe /F

UI solution For Windows users: I found that the top answers did not work for me, they seemed to be commands for Mac or Linux users. I found a simple solution that didn't require any commands to remember: open Task Manager (ctrl+shift+esc). Look at background processes running. Find anything Node.js and end the task.
After I did this the issue went away for me. As stated in other answers it's background processes that are still running because an error was previously encountered and the regular exit/clean up functions didn't get called, so one way to kill them is to find the process in Task Manager and kill it there. If you ran the process from a terminal/powerShell you can usually use ctrl+c to kill it.

Task Manager (ctrl+alt+del) ->
Processes tab ->
select the "node.exe" process and hit "End Process"

Just in case check if you have added this line multiple times by mistake
app.listen(3000, function() {
console.log('listening on 3000')
});
The above code is for express but just check if you are trying to use the same port twice in your code.

In windows users: open task manager and end task the nodejs.exe file, It works fine.

On Windows, I was getting the following error:
EADDRINUSE: address already in use :::8081.
Followed these steps:
Opened CMD as Admin
Ran the folowing
command netstat -ano|findstr "PID :8081"
got the following processes:
killed it via:
taskkill /pid 43144 /f
On MAC you can do like this:
raghavkhunger#MacBook-Air ~ % lsof -i tcp:8081
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
node 23722 username 24u IPv6 0xeed16d7ccfdd347 0t0 TCP *:sunproxyadmin (LISTEN)
username#MacBook-Air ~ % kill -9 23722

With due respect to all the answers in the form, I would like to add a point.
I found that when I terminate a node app on error using Ctrl + Z, the very next time when I try to open it got the same error EADDRINUSE.
When I use Ctrl + C to terminate a node app, the next time I opened it, it did without a hitch.
Changing the port number to something other than the one in error solved the issue.

using netstat to get all node processes with the port they are using and then kill the only one you want by PID
netstat -lntp | grep node
you will get all node processes
tcp6 0 0 :::5744 :::* LISTEN 3864/node
and then when you get the PID (3864) just kill the processes by PID
kill -HUP PID

You may use hot-node to prevent your server from crashing/ run-time-errors. Hot-node automatically restarts the nodejs application for you whenever there is a change in the node program[source] / process[running node program].
Install hot-node using npm using the global option:
npm install -g hotnode

How to stop Meteor?

The only answer on this question I saw - go start another copy on the different port.
Switching from one Meteor workspace to another
Okay, I see that I can run another one on the different port, BUT how to stop the first one?

I use this command:
kill -9 `ps ax | grep node | grep meteor | awk '{print $1}'`
Or, I run this if I'm on my local machine to kill remote processes:
ssh [user]#[server] <<'ENDSSH'
kill -9 `ps ax | grep node | grep meteor | awk '{print $1}'`
exit
ENDSSH

On OSX, go back to the term you opened to start meteor, and use CTRL+C to quit the process.

if Meteor is running on :3000 port:
kill -9 $(lsof -i :3000 -t);

Similar to Fernando's response, if you're on OSX you can quit the processes node and mongod using Activity Monitor.
quitting node will stop the server. The database will still be running and accepting incoming connections, so quitting mongod will turn off the database.

Enter command "Ctrl + C" on the terminal where the meteor process is running. This is the easiest way to kill the process in both Mac and Ubuntu. Not sure of Windows though.
Happy Coding!

In my case (Ubuntu 11.10) I open the System Monitor and kill manually the node and mongod processes.
Of course you can use also the terminal and kill these processes knowing their PID's.

An edit to John Devor's (accepted) answer: if you're editing your code with Atom, his command may kill the editor instances:
$ ps ax | grep node | grep meteor
19312 pts/2 Sl+ 0:16 /home/teo/.meteor/packages/meteor-tool/.1.1.4.e4elpj++os.linux.x86_64+web.browser+web.cordova/mt-os.linux.x86_64/dev_bundle/bin/node /home/teo/.meteor/packages/meteor-tool/.1.1.4.e4elpj++os.linux.x86_64+web.browser+web.cordova/mt-os.linux.x86_64/tools/main.js
19541 pts/2 Sl+ 0:02 /home/teo/.meteor/packages/meteor-tool/.1.1.4.e4elpj++os.linux.x86_64+web.browser+web.cordova/mt-os.linux.x86_64/dev_bundle/bin/node /home/teo/meteor/beari/dist/.meteor/local/build/main.js
24438 ? Sl 0:00 /usr/share/atom/atom --no-deprecation /home/teo/.atom/packages/linter-jshint/node_modules/jshint/bin/jshint --reporter /home/teo/.atom/packages/linter-jshint/node_modules/jshint-json/json.js --filename /home/teo/meteor/beari/beari.js -
Better to use a command like:
kill -9 `ps ax | grep node | grep meteor | grep -v atom | awk '{print $1}'`

When you are looking at the terminal with the unwanted meteor running just press Ctrl+C to turn off meteor.
To run more applications side by side run on a different port with the --port option

use sudo killall -9 node command. it will kill all the rprocess.

Actually, kill -9 kills meteor immediately, which is not a good idea. It's an emergency feature and should be applied only when regular kill (no signal specified) fails, as it prevents processes from running shutdown procedures.

the default port is 3000.If you want to run it in a different port use below
meteor run --port 3030
run this in two command prompt.If you want to stop use ctrl+c in necessary command prompt

Enter command "Ctrl + C" on the terminal where you want to stop process is running. This is the easiest way to kill the process in both Mac and Ubuntu and Windows.And you can use "meteor run --port portnumber" to run the two or more projects at the same time

In the terminal, I used: $ sudo killall -9 node (this kills all running node jobs)

It's so simple in my case, I always have two terminal tabs open, one for launching Meteor/stopping it and the other terminal for working the commands. So to stop it I just do the universal control+c to stop the working process.