---
title: not-found.js
description: API reference for the not-found.js file.
---
Next.js provides two conventions to handle not found cases:
- **`not-found.js`**: Used when you call the [`notFound`](/docs/app/api-reference/functions/not-found) function in a route segment.
- **`global-not-found.js`**: Used to define a global 404 page for unmatched routes across your entire app. This is handled at the routing level and doesn't depend on rendering a layout or page.
## `not-found.js`
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 return a `200` HTTP status code for streamed responses, and `404` for non-streamed responses.
```tsx filename="app/not-found.tsx" switcher
import Link from 'next/link'
export default function NotFound() {
return (
Not Found
Could not find requested resource
Return Home
)
}
```
```jsx filename="app/blog/not-found.js" switcher
import Link from 'next/link'
export default function NotFound() {
return (
Not Found
Could not find requested resource
Return Home
)
}
```
## `global-not-found.js` (experimental)
The `global-not-found.js` file lets you define a 404 page for your entire application. Unlike `not-found.js`, which works at the route level, this is used when a requested URL doesn't match any route at all. Next.js **skips rendering** and directly returns this global page.
This is useful when you can't build a 404 page using a combination of `layout.js` and `not-found.js`. This can happen in two cases:
- Your app has multiple root layouts (e.g. `app/(admin)/layout.tsx` and `app/(shop)/layout.tsx`), so there's no single layout to compose a global 404 from.
- Your root layout is defined using top-level dynamic segments (e.g. `app/[country]/layout.tsx`), which makes composing a consistent 404 page harder.
To enable it, add the `globalNotFound` flag in `next.config.ts`:
```tsx filename="next.config.ts"
import type { NextConfig } from 'next'
const nextConfig: NextConfig = {
experimental: {
globalNotFound: true,
},
}
export default nextConfig
```
Then, create a file in the root of the `app` directory: `app/global-not-found.js`:
```tsx filename="app/global-not-found.tsx" switcher
export default function GlobalNotFound() {
return (
404 - Page Not Found
This page does not exist.
)
}
```
Unlike `not-found.js`, this file must return a full HTML document, including `` and `` tags.
## Reference
### Props
`not-found.js` or `global-not-found.js` components do not accept any props.
> **Good to know**: In addition to catching expected `notFound()` errors, the root `app/not-found.js` and `app/global-not-found.js` files handle 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 exported UI.
## Examples
### Data Fetching
By default, `not-found` is a Server Component. You can mark it as `async` to fetch and display data:
```tsx filename="app/not-found.tsx" switcher
import Link from 'next/link'
import { headers } from 'next/headers'
export default async function NotFound() {
const headersList = await headers()
const domain = headersList.get('host')
const data = await getSiteData(domain)
return (
Not Found: {data.name}
Could not find requested resource
View all posts
)
}
```
```jsx filename="app/not-found.jsx" switcher
import Link from 'next/link'
import { headers } from 'next/headers'
export default async function NotFound() {
const headersList = await headers()
const domain = headersList.get('host')
const data = await getSiteData(domain)
return (
Not Found: {data.name}
Could not find requested resource
View all posts
)
}
```
If you need to use Client Component hooks like `usePathname` to display content based on the path, you must fetch data on the client-side instead.
### Metadata
For `global-not-found.js`, you can export a `metadata` object or a [`generateMetadata`](/docs/app/api-reference/functions/generate-metadata) function to customize the ``, `<meta>`, and other head tags for your 404 page:
```tsx filename="app/global-not-found.tsx" switcher
export const metadata = {
title: 'Not Found',
description: 'The page you are looking for does not exist.',
}
export default function GlobalNotFound() {
return (
<div>
<h1>Not Found</h1>
<p>The page you are looking for does not exist.</p>
</div>
)
}
```
## Version History
| Version | Changes |
| --------- | --------------------------------------------------- |
| `v15.4.0` | `global-not-found.js` introduced (experimental). |
| `v13.3.0` | Root `app/not-found` handles global unmatched URLs. |
| `v13.0.0` | `not-found` introduced. |