---
title: not-found.js
description: API reference for the not-found.js file.
---

The **not-found** file is used to render UI when the [`notFound`](/docs/app/api-reference/functions/not-found) function is thrown within a route segment. Along with serving a custom UI, Next.js will also return a `404` HTTP status code.

```tsx filename="app/blog/not-found.tsx" switcher
import Link from 'next/link'

export default function NotFound() {
  return (
    <div>
      <h2>Not Found</h2>
      <p>Could not find requested resource</p>
      <Link href="/">Return Home</Link>
    </div>
  )
}
```

```jsx filename="app/blog/not-found.js" switcher
import Link from 'next/link'

export default function NotFound() {
  return (
    <div>
      <h2>Not Found</h2>
      <p>Could not find requested resource</p>
      <Link href="/">Return Home</Link>
    </div>
  )
}
```

> **Good to know**: In addition to catching expected `notFound()` errors, the root `app/not-found.js` file also handles any unmatched URLs for your whole application. This means users that visit a URL that is not handled by your app will be shown the UI exported by the `app/not-found.js` file.

## Props

`not-found.js` components do not accept any props.

## Data Fetching

By default, `not-found` is a Server Component. You can mark it as `async` to fetch and display data:

```tsx filename="app/blog/not-found.tsx" switcher
import Link from 'next/link'
import { headers } from 'next/headers'

export default async function NotFound() {
  const headersList = headers()
  const domain = headersList.get('host')
  const data = await getSiteData(domain)
  return (
    <div>
      <h2>Not Found: {data.name}</h2>
      <p>Could not find requested resource</p>
      <p>
        View <Link href="/blog">all posts</Link>
      </p>
    </div>
  )
}
```

```jsx filename="app/blog/not-found.jsx" switcher
import Link from 'next/link'
import { headers } from 'next/headers'

export default async function NotFound() {
  const headersList = headers()
  const domain = headersList.get('host')
  const data = await getSiteData(domain)
  return (
    <div>
      <h2>Not Found: {data.name}</h2>
      <p>Could not find requested resource</p>
      <p>
        View <Link href="/blog">all posts</Link>
      </p>
    </div>
  )
}
```

## Version History

| Version   | Changes                                             |
| --------- | --------------------------------------------------- |
| `v13.3.0` | Root `app/not-found` handles global unmatched URLs. |
| `v13.0.0` | `not-found` introduced.                             |
