“Port 4200 is already in use” when running the ng serve command

Question

I am learning angular 2 and for the first time I am using the angular CLI project to create a sandbox project.

I was able to run the command "ng serve" and it works great. I wanted to stop it from running so I ran "Control Z".

When I tried to run the "ng-serve" command again it gives me "Port 4200 is already in use."

I ran "PS" to get a list of the PID and killed the PID for the angular-cli and ran "ng-serve" again still it gives the same port in use error.

Answer 1

This is what I used to kill the progress on port 4200

For linux users:

sudo kill $(sudo lsof -t -i:4200)

You could also try this:

sudo kill `sudo lsof -t -i:4200`

For windows users:

Port number 4200 is already in use. Open the cmd as administrator. Type below command in cmd:

netstat -a -n -o

And then, find port with port number 4200 by right click on terminal and click find, enter 4200 in "find what" and click "find next": Let say you found that port number 4200 is used by pid 18932. Type below command in cmd:

taskkill -f /pid 18932

For UNIX:

alias ngf='kill -9  $(lsof -t -i:4200);ng serve'

Now run ngf (instead of ng serve) in terminal from the project folder. This will kill all processes using the port 4200 and runs your Angular project.

Answer 2

Open your cmd.exe as administrator,

then Find the PID of port 4200

netstat -ano | findstr :4200

Here i have 3 PID :

• Red one is from "ng-serve" (127.0.0.1:4200) that LISTENING
• Green one is from "your browser"

kill only port 4200 (kill the red PID):

taskkill /PID 15940 /F

note : kill the green one will only lead your browser closed by force.

now you can do "ng-serve" to start your angular app at the same port 4200

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Additional Stuff :

One liner : After looking a way to optimize this, Here is the One-liner command of this answer : (special thanks to : Josep Alsina for this tips)

for /f "tokens=5" %a in ('netstat -ano ^| find "4200" ^| find "LISTENING"') do taskkill /f /pid %a

Answer 3

On Mac OS X you need the following command:

sudo lsof -t -i tcp:4200 | xargs kill -9

Remember you need to kill Angular's web server with Command+C.

Answer 4

Not ctrl+Z, you must run for stop ctrl+C

Answer 5

Use this command to kill ng:

pkill -9 ng

Answer 6

When you use Ctrl+Z, you are going to suspend a running task but not to kill it. You can later use command fg to resume the task. If you want to quit ng serve, you should use Ctrl+C instead, in which will also release the 4200 port.

Answer 7

ng serve --port <YOUR_GIVEN_PORT_NUMBER>

You should try above command to run on your given port.

Answer 8

In summary there are more than one solution : 1 ) By using another port to define port number ,

ng serve --open --port 4201

2) by killing the process

ctrl + c // for kill
Close all node terminal which is related for running the app.

3) Type

netstat -a -n -o

in command prompt then find the related port PID and kill it by

taskkill /F /PID (pid number)

4) Type netstat -ano|findstr :4200

took the foreign address PID which contain the port number and then kill it by

taskkill /PID (pid number)/F

Answer 9

Right now you can set --port 0 to get a free port.

ng serve --port 0 // will get a free port for you

Answer 10

For Windows:

Open Command Prompt and

type: netstat -a -o -n

Find the PID of the process that you want to kill.

Type: taskkill /F /PID 16876

This one 16876 - is the PID for the process that I want to kill - in that case, the process is 4200 - check the attached file.you can give any port number.

Now, Type : ng serve to start your angular app at the same port 4200

Answer 11

I am sharing this as the fowling two commands did not do the job on my mac:

sudo kill $(sudo lsof -t -i:4200)

sudo kill `sudo lsof -t -i:4200`

The following one did, but if you were using the integrated terminal in Visual Code, try to use your machine terminal and add the fowling command:

lsof -t -i tcp:4200 | xargs kill -9

Answer 12

We can forcefully kill the port by following command.

kill -2 $(lsof -t -i:4200)

Answer 13

netstat -anp | grep ":4200"

This will tell you who's got the port.

Answer 14

The most simple one line command:

 sudo fuser -k 4200/tcp

Answer 15

ng serve --port 4201 --live-reload-port 4200

and access using localhost:4201

This should work as a temporary solution.

or

try listing port usage using
lsof -i:4200
and kill it manually using
sudo kill -9 <Process PID using port 4200>

Answer 16

To stop all the local port running in windows, use this simple comment alone instead searching for pid separatly using netstat,

It find all the pid and stop the local port which is currently running,

taskkill /im node.exe /f

Answer 17

VScode terminal in Ubuntu OS use following command to kill process

lsof -t -i tcp:4200 | xargs kill -9

Answer 18

With ctrl + z you put the program in the background. On Linux you can get the session back in the foreground with the following command:

fg ng serve

You don't need to kill the process.

Answer 19

Just restart the IDE you are using, then it will work.

Answer 20

In my case none of the above mentioned worked.

UBUNTU 18.04 VERSION

Below command worked.

sudo kill -9 $(lsof -i tcp:4200 -t)

Answer 21

It says already we are running the services with port no 4200 please use another port instead of 4200. Below command is to solve the problem

ng serve --port 4300

Answer 22

If you are using VSCode, you have the option to kill terminal and add a new terminal. Close the tab and open a new tab. It worked for me.

Edited: Use ctrl+c and press y. With out killing terminal also, You can proceed. If you want to open a new instance of visual studio and run a different application , you can use ng serve --port 4401.

Answer 23

Port 4200 is already in use.Use -port to specify a different port error Reasons An existing application(not angular) in your system using the port number 4200. This is a very rare scenario. In this case, you need to change the port number of angular application as mentioned below. You already ran ng serve and to exit the application you typed Control Z (Ctrl+Z), And then you typed ng serve then you will get port 4200 is already in use_ error. In this case, you need to kill the previous process.

To change the port number for our angular application use the below command

ng serve --port 4201

Now type ng serve

Our angular application will be running on http://localhost:4201

To fix port 4200 is already in use error in In Mac & Linux OS (Ubuntu etc) use the following commands

sudo kill $(sudo lsof -t -i:4200) Or
sudo kill `sudo lsof -t -i:4200` Or
sudo lsof -t -i tcp:4200 | xargs kill -9

In Window operating system open command prompt. Use the following command to fix port 4200 is already in use error.

netstat -a -n -o | findStr "4200"`

Take the process id and kill the process using the following command

taskkill -f /pid 11128

Answer 24

You can also try with this to run your application in visual studio code -:

ng serve --open --port 4201

you can give any port number.

Answer 25

you can use fuser -k 4200/tcp if it is Linux Operating system

Answer 26

Kill process and close the terminal which you used for running the app on that port.

Answer 27

Instead of killing the whole process or using ctrl+z, you can simply use ctrl+c to stop the server and can happily use ng serve command without any errors or if you want to run on a different port simply use this command ng serve --port portno(ex: ng serve --port 4201).

Answer 28

For Ubndu 18.04 sudo lsof -t -i tcp:3000 | xargs kill -9

Its happen when port was unsucessfully terminated so this command will terminat it 4200 or 3000 or3300 any

Answer 29

It seems like another program is using your default port 4200. Good thing is, ports above 4200 are usually free. Just pick another one. For example:

ng serve --port 4210

Answer 30

On my Ubuntu i had typo crl+z to close terminal and after that i couldn't acces localhost:4200. The only solutin was to do:

$ sudo fuser -k 4200/tcp

and after that restart the server.