React version 19 error : Hydration failed because the server rendered HTML didn't match the client

I am new to React.js and got a setup of react application through:

npx create-next-app@latest projectname

After taking some minutes, setup completed with error:

I tried to research this error but didn't found a solution.

I tried to set up a React application and was expecting it to run smoothly as per documentation provided on https://react.dev/learn/start-a-new-react-project

In package.json:

React version is 19.0.0

Next.js version is 15.1.2

Below is the code of src\app\page.js :

<div className="demo"> Hello world </div>

This type of error often occurs when you use an unsymmetrical element that is not intended to be used in a certain way, such as wrapping a <p> tag inside another <p> tag. You can read more about it here:

• How to solve React hydration error in Next.js
• React hydration error - Next.js documentation

1 of the solution provided in second documentation is :

suppressHydrationWarning

i have added this option in top most parent tag and error gone.