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Node.js Port 3000 already in use but it actually isn't?

I have been working with a node.js project for a few weeks and it has been working great. Usually, I use npm start to run my app and view it in a browser on localhost, port 3000.

Today, I started to get the following error while using npm start:

Server started on port 3000                                                                                                                                                                                         
Port 3000 is already in use 

I have checked the resource monitor and I have no other process running on port 3000. Why would I be getting this error message?

In my app.js I have the following code to set the port...is this incorrect? It worked fine before so I'm not sure what I am doing wrong.

// Set Port
app.set('port', (process.env.PORT || 3000));
app.listen(app.get('port'), function() {
    console.log('Server started on port '+app.get('port'));
});

Thanks for the help!

EDIT:

I have tried running netstat and TCPView to check what process is using the port, but there is nothing using that port. I also tried restarting my laptop but I still get the same error.

There is another process that uses this port, it is certain. Which os are you trying to ? You can google it like 'find which prosess uses port' for your operating system
The favicon will be cached. You could also try netstat in a command prompt, or connecting to localhost:3000 with a telnet equivalent - PuTTY, for example.
I notice you get "Port 3000 is already in use" after "Server started on port 3000" - is something in your app attempting to start listening again on the same port?
My guess is that you have two app.listen() statements in your app on another .listen() that is also trying to start a server on that port. The first one works, the second one reports the error. Search your code for .listen.

A
Ashwani Panwar

You can search on how to kill that process.

For Linux/Mac OS search (sudo) run this in the terminal:

$ lsof -i tcp:3000
$ kill -9 PID

On Windows:

netstat -ano | findstr :3000
tskill typeyourPIDhere 

change tskill for taskkill in git bash


I've tried a number of other solutions on windows, but this one found the odd process that was hogging the port. Earned an upvote for including also the linux approach in addition to working on windows.
tskill didn't working for me on windows. taskkill /F /PID myPIDhere - this working
I get nothing with only lsof but with sudo lsof I get something, and killing that process solved this problem.
Is there a way to dynamically get the PID for the running process and kill it? For some reason, I have to do this every time I deploy to prod manually. Side note, sure if this is related to PM2 or not.
taskkill did not work for me on git-bash, but tskill did. thanks.
P
Penny Liu

Maybe you can take this as reference. This single command line can kill the process running on given port.

npx kill-port 3000

https://i.stack.imgur.com/uqjmN.png

To kill multiple ports.

npx kill-port 3000 8080 4200

npx kill-port 3000 worked for me. Thanks @Penny
I had no idea this package existed. Only 7:30am and my day is already made.
Wow... this definitely saved my evening
yeah It's working thanks, but what package it installed ?
Awesome! Worked great. I love simple solutions.
A
Abhay

Sometimes it happens, as @sova proposed This happens to me sometimes, EADDR in use. Typically there is a terminal window hiding out in the background that is still running the app. And that's also right with me.

It happens, when you have opened terminal for long time, yeah you have right, you have stop the process. But sometimes it didn't stop in the background. So best solution is that you close the terminal and start it again. It will solves your problem. becuase in my case it works.

Also,

sudo lsof -i:<PORT_NO>

close the instance for present time but unable to stop the process in background. So for one time,

sudo kill <PID>

works, but again when we update our code and save, this problem occurs again as with Nodemon.

So exit the terminal will solve the problem. OR

  killall -9 node

Neither the lsof or netstat returned anything, yet there still seemed to be some process using the port. After killall -9 node I was able to run the server locally.
thanks for the killall -9 node command. it worked on goorm IDE
killall -9 node it worked. Thanks!
M
Mahyar

I had the same problem. (The below steps work fine on Windows 10):

Open Task manager (press Ctrl+Alt+Delete) Select the 'Processes tab' Search for 'Node.js: Server-side JavaScript' Select it and click on 'End task' button

Now you can run npm start.

Hope it helps you.


i
i_am_daim

I also encountered the same issue. The best way to resolve is (for windows):

Go to the Task Manager. Scroll and find a task process named. Node.js: Server-side JavaScript End this particular task.

There you go! Now do npm start and it will work as before!


P
PRAKASH THOMAS VARGHESE

For windows, The Task Manager would definitely show a node process running. Try to kill the process, it will solve the problem.


A
Afeesudheen

Killing a process that owns port 3000

First, let’s take a look at how we can kill a process that has a port open.

Using the lsof command, we can retrieve the PID that has the given port:

$ lsof -i :3000 -t
12345

Then we can kill this process just by doing:

$ kill 12345

Let’s turn this into a one-liner:

lsof -i 3000 -t | xargs kill

If you’re using an environment variable to set the server port, we can specify that instead of hardcoding our values:

lsof -i ${PORT} -t | xargs kill

Lastly, we can default to port 3000 if the environment variable isn’t set:

lsof -i ${PORT:-3000} -t | xargs kill

Getting nodemon to execute hooks

Nodemon lets you set up event hooks through nodemon.json configuration file:

{
  "events": {
    "crash": "sh -c 'lsof -i :${PORT:-3000} -t | xargs kill'"
  }
}

This will cause nodemon to execute sh -c 'lsof -i :${PORT:-3000} -t | xargs kill command whenever your app crashes, thereby killing the child process it spawned that’s keeping the port open.

or you can try this one

fuser -k PORT-NO/tcp

Eg:

fuser -k 3000/tcp

You can try this aswell

fuser -n tcp -k PORT-NO

Eg:

fuser -n tcp -k 3000

This is quite a nice and clean solution to killing a process. Have to look how to do this up every time, and this is the nicest solution I've seen yet!
Im experiencing this issue although no processes are returning from lsof -i :3000 -t =\
@xaunlopez try this one fuser -k port-number/tcp
S
Salah Ben Bouzid
 killall -9 node

the above command can exit vs code ssh connection when you are developing remotely and kill all node processes that can lead to problems especially if you have some apps on production using node , there is a better way to do it by 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 -9 PID

or

   kill -HUP PID 

I had the same error on Ubuntu so what helped me was 1) make sure you haven't already assigned Port to a variable and are still using quotes ("port") to get your port connection instead of the variable. Secondly, on Ubuntu you can use Run sudo netstat -lp to figure out what is using that port
a
aygunyilmaz

I was using express server with nodemon on NodeJS. I got the following message and it seems an error:

$ node ./bin/www
Port 3000 is already in use

There is a general solution that if you terminate all node server connections, you can add this code in your package.json file:

"scripts": {
    "start": "node ./bin/www",
    "stop": "taskkill -f -im node.exe"
},

In addition, I've found several solutions windows command and bash on Win 10 x64.

All my notes are here:

# Terminate all NodeJS Server Connections

$ taskkill -f -im node.exe
SUCCESS: The process "node.exe" with PID 14380 has been terminated.
SUCCESS: The process "node.exe" with PID 18364 has been terminated.
SUCCESS: The process "node.exe" with PID 18656 has been terminated.

# Example: Open the Windows Task Manager and see "node.exe" PID number on Windows

>> Command Line
$ netstat /?
$ netstat -a -n -o
$ netstat -ano

# Kill a process in Windows by Port Number (Example)

For Help:

$ taskkill /?
$ tskill /?

Code 1:

$ taskkill -pid 14228
ERROR: The process with PID 14228 could not be terminated.
Reason: This process can only be terminated forcefully (with /F option).

Code 2:

$ taskkill -f -pid 14228
SUCCESS: The process with PID 14228 has been terminated.

Code 3:

$ tskill 14228

# Command line for looking at specific port

in cmd:

$ netstat -ano | find "14228"

in bash:

$ netstat -ano | grep "14228" or $ netstat -ano | grep 14228

# Find node.exe using "tasklist" command

in cmd:

$ tasklist | find "node"

in bash:

$ tasklist | grep node
$ tasklist | grep node.exe
node.exe                     14228 Console                    2     48,156 K
node.exe                     15236 Console                    2     24,776 K
node.exe                     19364 Console                    2     24,428 K

You are the Greatest :-) The line: "stop": "taskkill -f -im node.exe" in the package.json did it for me. I work remote with SSH. I had to look for a solution I think more as one Hour. All the kill commands etc. did not work.
I am using netstat -ano | find "14228" and want to use this with taskkill /PID xxx. I am not able to pipe it with | nor with >. It is throwing up on me with a wrong format error. What am I missing? These are the two : netstat -ano | find "14228" | taskkill /PID xxx or netstat -ano | find "14228" > taskkill /PID xxx. I have tried this netstat -ano | find "14228" | ( set /P var= && set var ) > taskkill /PID ........
J
James Smith

I've seen the same thing and tried all the suggestions above without success. Here are steps that resolve it for me: - turn off wifi - npm start (this should work) - turn on wifi

I'm not exactly sure what the root issue is but that resolved it for me.


I just had this happen to me as well. netstat -ano didn't list anything using port 3000.
Holy hell, this solved it for me too as obviously nothing was running on port 3000. I started having this issue after a Windows update. Never thought about turning WiFi off. Thank you for solving this :)
for me this helped. I had turned on wifi at some point in the day. I usually use the Ethernet. So i completely cut off wifi and then rebooted it. Everything back to working again. Wow. Without your hint, I would have been wondering off for hours maybe.
This worked for me too. Then I tried WiFi on and VPN off...also worked. Anyone know why this might be?
M
Mayur

I was facing the same issue today since I found the solution.

The issue is because there were node services is running in the background even if nodemon restarts.

I've gone through many answers but all come with multiple commands. There is the simple command I found for my case

sudo pkill node

This will terminate all the running processes from the node and your nodemon will start working as expected.


s
sova

This happens to me sometimes, EADDR in use. Typically there is a terminal window hiding out in the background that is still running the app. You can stop process with ctrl+C in the terminal window.

Or, perhaps you are listening to the port multiple times due to copy/pasta =)


Thanks for the help! I don't have any other terminal windows open, anything else I should check?
find any node or npm process and end it. if still you have a funk, reboot machine, or just pick a different port to work with. There's really no reason it must be port 3000 or 8080
I just created a new node app and started it on port 3000 and that one seems to work fine, but when I try to run my existing project, it says the port is in use. Have you ever had this issue?
@user2573690 i have not come across that before, but maybe you have multiple js files (like an app.js and an index.js) where one is calling .listen() multiple times?
Thank you! I managed to figure it out, I was listening to the port multiple times, copy/pasta accident! If you can edit your answer and add that piece, I will mark it. Again, thank you!
O
Omar bakhsh

Open Task Manager (press Ctrl+Alt+Del Select the 'Processes Tab' Search for 'Node.js: Server-side JavaScript' Select it and click on 'End task' button


t
test30

I have spent 2h on finding out why EADDRINUSE wasn't allowing me to sart an app (other node-express servers were ok)... it started working after adding lazyConnect: true, to datasource configuration.

Don't ask me why it helped. I do not know. I am putting this info here just for people having the same issue.


upvoted for the willingness to help AND a solution that may help find the root cause.
sorry, where is the setting put?
u
umutyerebakmaz

If you want to close only one port, just run this command. kill -9 $(lsof -t -i:3000)

The difference between pkill and kill is someone process clay. In kill you apply a filter. you just stop the port you want.

The pkill command closes all node processes. pkill -9 node

Use pkill to avoid memory leaks that occur occasionally during development. if there is more than one node, it kills them all.

The use of scripts in package.json is also exemplified.

"scripts": {
    "server:start": "cd server && yarn start",
    "server:restart": "cd server && yarn restart",
    "frontend:start": "cd frontend && yarn start",
    "frontend:restart": "kill -9 $(lsof -t -i:4200) && yarn start:frontend"
},
"scripts": {
    "start": "nodemon --watch 'src/**/*.ts' --ignore 'src/**/*.spec.ts' --exec 'ts-node' src/index.ts",
    "restart": "pkill -9 node && start",
    "kill": "pkill -9 node"
},

t
towith

I have encounter a weird port problem on win10 recently, can not start server process listen on port 8080, and I changed it to 18080 , then it works, but after a while, same problem appear again. But I can not find any process use the port, I have tried currpots and netstat , none of them work, and I try open port by

python -m http.server 18080
python -m http.server 18081
python -m http.server 18082
python -m http.server 18083
python -m http.server 18084
...

, Most says similar message of "port already in use" Fortunately, I searched and got the reason. By

netsh interface ipv4 show excludedportrange protocol=tcp

Can see some port are exclude for use, through these port not opened and listened. And by

net stop winnat

Most excluded port are released, these port can be used then.


net stop winnat - I just forgot that command. Needed it a few weeks ago and today because of the same problem (appears sometimes... why?!). Will add this to autostart.
Seems the winnat service is started by windows hyper-v
o
obrienk

This is an old question, but none of the responders seem to have actually read it. I had the same problem and the issue was that Windows sometimes reserves blocks of ports and stops you from using them. The port does not show up via netstat or any other tool. You can read about it here:

Essentially you can tell Windows to leave your port alone with this:

netsh int ipv4 add excludedportrange tcp startport=3000 numberofports=1 store=persistent

Thanks a lot. This solved my problem. I've been trying to find a solution for the last couple of hours.
After trying all the previous solutions I got here. There was no visible process running on port 3000. This solution worked for me. Thank you.
I
Imran Khan

It happens when no task is listed with a command

lsof -i:3000

And still, you get an error

Error: listen EADDRINUSE: address already in use 0.0.0.0:3000

One reason is that in Nginx conf.d check none of configuration is listening on port 3000


This does not fix the user's problem or help fixing it, please look on how to write a good answer
A
Amanullah Aman

I got this problem using Git Bash on Windows. I run npm start, or node app.js. After terminating it with Ctrl+C shortly and trying to start the server again using npm start or node app.js then I get this error message.

When I do this with the regular Windows Command Prompt, however, it works fine.

Or You can do it in another way. Open the Task Manager and Find the "Node.js:Server-side JavaScript" row. Select that and end task. It should work now.

Thanks.


i
isherwood

https://i.stack.imgur.com/1hOsY.png

Open your command prompt and first run this command:

netstat -ano | findstr :7001

And then run this command:

taskkill /PID 2820 /F

s
sznowicki

Came from Google here with a solution for High Sierra.

Something changed in the networking setup of macos and some apps (including ping) cannot resolve localhost.

Editing /etc/hosts seems like a fix:

cmd: sudo nano /etc/hosts/ content 127.0.0.1 localhost

Or simply (if you're sure your /etc/hosts is empty) sudo echo '127.0.0.1 localhost' > /etc/hosts


Z
Zuhair Taha

For windows users, you can use CurrPorts tool to kill ports under usage easily

https://i.stack.imgur.com/LldYw.png


M
Muhammad Ashfaq

For windows user, Just simple stop all processes of Node.js in Task Manager

Hope it will help


S
Servet

if you called app.listen function many time on same port, you can get this error.

You can check your codes for any loop


Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center.
M
Mohit Singh

Try opening the localhost in your browser. Just type: localhost:3000 in the address bar.

If the app opens-up, it means your previous npm run is still active. Now, you can just make changes to the code and see the effects if you are designing the same app, or if you wanna run another app, just tweak the code (in index.js of previously running app) a little-bit and (probably refresh the browser tab) to make it crash ;)..... Now go run npm run start again from your new app directory. Hope this helps! :)

or

You can open the Task Manager (WINDOWS_KEY+X > Task Manager) and you'll see the "Node.js:Server-side JavaScript" row. Select that and end task....It should work now!!



If not, change the .env file of your app to include port:3002 and run the new app. This will allow you to run two separate apps on different ports. Cheers!!


O
Oben Desmond

Simple in linux

Open your terminal

Free port from processes -> kill $(lsof -t -i:$port)


P
Penny Liu

Before running nodemon, Please start mongod first. You will never get this error.


t
tnoel999888

It may be an admin process running in the background and netstat doesn't show this.
Use tasklist | grep node to find the PID of this admin process and then kill PID


M
Muhammad Saleh

if you are using webstorm just make sure your default port is not 3000 from file -> settings -> Build, Execution, Deployment -> Debugger And there change

Built-in server port

and set it to "63342" or see this answer Change WebStorm LiveEdit Port (63342)


K
Kalkhas

In package.json scripts inlcude:

"start": "nodemon app.js --delay 1500ms"

I believe the issue was for me the time that the old port was not shutting down in time by nodemon for the restart. I experienced the issue using multer.


Adjust the delay as required.