Troubleshooting NextJS Hydration Error

title_thumbnail(Troubleshooting NextJS Hydration Error)

Table of Contents

Title: Troubleshooting React 18: Hydration Issues with Server-Side Rendering

Introduction

If you’ve encountered the error “Hydration failed because the initial UI does not match what was rendered on the server,” while implementing server-side rendering (SSR) in your React 18 application, you’re not alone. In this blog post, we will explore the possible causes of this error and provide troubleshooting solutions to help you resolve it.

Possible Causes

There are several potential reasons why you might encounter the hydration error in your React 18 SSR setup. Let’s explore some common causes:

Improper HTML Element Arrangement

One common cause is improper arrangement of HTML elements. Libraries like NextJS might have specific requirements for how elements should be wrapped. For example, using a `

` tag to wrap `

` or other semantic elements can trigger the hydration error. Ensure that your HTML structure follows the guidelines provided by the library you are using.


import Image from 'next/image';

export const IncorrectComponent = () => {
  return (
    
      <div>This is not correct and should never be done because the p tag has been abused</div>
      <Image src='/vercel.svg' alt='' width='30' height='30'/>
    
  );
}

export const CorrectComponent = () => {
  return (
    <div>
      <div>This is correct and should work because a div is really good for this task.</div>
      <Image src='/vercel.svg' alt='' width='30' height='30'/>
    </div>
  );
}

Incompatible Packages

In some cases, incompatible packages can cause the hydration error. If a package modifies the window object, SSR might fail. To address this issue, delay rendering the component until the DOM is fully loaded. One way to achieve this is by using the `useEffect` hook to wait for the DOM to load before rendering the component.


const Index = () => {
  const [domLoaded, setDomLoaded] = useState(false);

  useEffect(() => {
    setDomLoaded(true);
  }, []);

  return (
    <>
      {domLoaded && (
        <Swiper>
          <div>Test</div>
        </Swiper>
      )}
    </>
  );
};

export default Index;

Invalid HTML Tag Nesting

Another common issue is invalid nesting of HTML tags. For example, using a `

` inside a `

` or a `

` inside a `` can trigger the hydration error. Ensure that all your tags are properly nested and adhere to the HTML standards.



<table>

<tbody>

<tr>

<td>a</td>


<td>b</td>

</tr>

</tbody>

</table>

Solutions

Now that we understand some of the possible causes of the hydration error, let’s explore the solutions:

Review HTML Element Arrangement

Double-check the arrangement of HTML elements in your code, especially when using SSR libraries like NextJS. Ensure that you are following the recommended guidelines and avoid nesting incompatible tags within each other.

Verify Package Compatibility

If you suspect that an external package is causing the issue, review its documentation and check for any known compatibility issues with SSR. When necessary, delay rendering the component until the DOM has fully loaded to avoid conflicts with packages modifying the window object.

Validate HTML Tag Nesting

Inspect your code for any invalid or misnested HTML tags. Make sure all tags are properly nested and adhere to the HTML standards. Validate your code using an HTML validator to catch any potential errors.

Conclusion

The “Hydration failed because the initial UI does not match what was rendered on the server” error can be frustrating, but with the troubleshooting steps outlined in this blog post, you should be able to identify and resolve the issue in your React 18 SSR application. Remember to review your HTML element arrangement, package compatibility, and validate HTML tag nesting to ensure a successful server-side rendering experience. Happy coding!

reference :

reactjs