Upgrade to React 19
Upgrading an existing React application to version 19 only requires two steps.
If you are already using the latest version of React, you can skip this section.
Step 1: Install React 19
To install the latest version, from your project folder run the following from the terminal:
npm i react@latest react-dom@latestStep 2: Use the new root API
In order to take advantage of React 19's concurrent features you'll need to use the new root API for client rendering.
// Before import ReactDOM from 'react-dom';
ReactDOM.render( <h1>Hello React!</h1>, document.getElementById('root') );
// After import { createRoot } from 'react-dom/client';
createRoot(document.getElementById('root')).render( <h1>Hello React!</h1> );Your application will work without using the new root API. If you continue to use ReactDOM.render your application will behave like React 17.