Something is already running on port 3000

Question

I have tried to run my project on my localhost but it is saying Something is already running on your port 3000.

Answer 1

 

On React - you can run an already created React single-page application (SPA) by

npm start command.

That may start your locally hosting development server and runs your app at:

http://localhost:3000/ which is equivalent to: 127.0.0.1:3000 address

127.0.0.1 is the default localhost IP number while the default port number set by

create-react-app package is 3000.

When getting: “Something is already running on port 3000" failure error message you may think that the port captured by another process running on your machine but you’ll find that it is captured permanently as if it runs on 0.0.0.0:3000 address

Solution:

In your project libraries created by create-react-app script navigate to:

node_modules/react-scripts/scripts/start.js

While running npm start command - the start.js script is being called and executed

There at start.js file in you editor find the above line:

const HOST = process.env.HOST || '0.0.0.0';

 and change it to:

const HOST = process.env.HOST || '127.0.0.1';

 

save and run your web app again at: http://localhost:3000/ or http://127.0.0.1:3000