Nuxt/docs/content/2.guide/2.features/7.error-handling.md

# Error Handling

## Handling errors

Nuxt 3 is a full-stack framework, which means there are several sources of unpreventable user runtime errors that can happen in different contexts:

1. Errors during the Vue rendering lifecycle (SSR + SPA)
1. Errors during API or Nitro server lifecycle
1. Server and client startup errors (SSR + SPA)

### Errors during the Vue rendering lifecycle (SSR + SPA)

You can hook into Vue errors using [`onErrorCaptured`](https://vuejs.org/api/composition-api-lifecycle.html#onerrorcaptured).

In addition, Nuxt provides a `vue:error` hook that will be called if any errors propagate up to the top level.

If you are using an error reporting framework, you can provide a global handler through [`vueApp.config.errorHandler`](https://vuejs.org/api/application.html#app-config-errorhandler). It will receive all Vue errors, even if they are handled.

#### Example with global error reporting framework

```js
export default defineNuxtPlugin((nuxtApp) => {
  nuxtApp.vueApp.config.errorHandler = (error, context) => {
    // ...
  }
})
```

### Server and client startup errors (SSR + SPA)

Nuxt will call the `app:error` hook if there are any errors in starting your Nuxt application.

This includes:

* running Nuxt plugins
* processing `app:created` and `app:beforeMount` hooks
* mounting the app (on client-side), though you should handle this case with `onErrorCaptured` or with `vue:error`
* processing the `app:mounted` hook

### Errors during API or Nitro server lifecycle

You cannot currently define a server-side handler for these errors, but can render an error page (see the next section).

## Rendering an error page

When Nuxt encounters a fatal error, whether during the server lifecycle, or when rendering your Vue application (both SSR and SPA), it will either render a JSON response (if requested with `Accept: application/json` header) or an HTML error page.

You can customize this error page by adding `~/error.vue` in the source directory of your application, alongside `app.vue`. This page has a single prop - `error` which contains an error for you to handle.

When you are ready to remove the error page, you can call the `clearError` helper function, which takes an optional path to redirect to (for example, if you want to navigate to a 'safe' page).

::alert{type="warning"}
Make sure to check before using anything dependent on Nuxt plugins, such as `$route` or `useRouter`, as if a plugin threw an error, then it won't be re-run until you clear the error.
::

### Example

```vue [error.vue]
<template>
  <button @click="handleError">Clear errors</button>
</template>

<script setup>
const props = defineProps({
  error: Object
})

const handleError = () => clearError({ redirect: '/' })
</script>
```

## Error helper methods

### `useError`

* `function useError (): Ref<any>`

This function will return the global Nuxt error that is being handled.

::ReadMore{link="/api/composables/use-error"}
::

### `createError`

* `function createError (err: { cause, data, message, name, stack, statusCode, statusMessage, fatal }): Error`

You can use this function to create an error object with additional metadata. It is usable in both the Vue and Nitro portions of your app, and is meant to be thrown.

If you throw an error created with `createError`:

* on server-side, it will trigger a full-screen error page which you can clear with `clearError`.
* on client-side, it will throw a non-fatal error for you to handle. If you need to trigger a full-screen error page, then you can do this by setting `fatal: true`.

### Example

```vue [pages/movies/[slug].vue]
<script setup>
const route = useRoute()
const { data } = await useFetch(`/api/movies/${route.params.slug}`)
if (!data.value) {
  throw createError({ statusCode: 404, statusMessage: 'Page Not Found' })
}
</script>
```

### `showError`

* `function showError (err: string | Error | { statusCode, statusMessage }): Error`

You can call this function at any point on client-side, or (on server side) directly within middleware, plugins or `setup()` functions. It will trigger a full-screen error page which you can clear with `clearError`.

It is recommended instead to use `throw createError()`.

::ReadMore{link="/api/utils/show-error"}
::

### `clearError`

* `function clearError (options?: { redirect?: string }): Promise<void>`

This function will clear the currently handled Nuxt error. It also takes an optional path to redirect to (for example, if you want to navigate to a 'safe' page).

::ReadMore{link="/api/utils/clear-error"}
::

## Rendering errors within your app

Nuxt also provides a `<NuxtErrorBoundary>` component that allows you to handle client-side errors within your app, without replacing your entire site with an error page.

This component is responsible for handling errors that occur within its default slot. On client-side, it will prevent the error from bubbling up to the top level, and will render the `#error` slot instead.

The `#error` slot will receive `error` as a prop. (If you set `error = null` it will trigger re-rendering the default slot; you'll need to ensure that the error is fully resolved first or the error slot will just be rendered a second time.)

::alert{type="info"}
If you navigate to another route, the error will be cleared automatically.
::

### Example

```vue [pages/index.vue]
<template>
  <!-- some content -->
  <NuxtErrorBoundary @error="someErrorLogger">
    <!-- You use the default slot to render your content -->
    <template #error="{ error }">
      You can display the error locally here.
      <button @click="error = null">
        This will clear the error.
      </button>
    </template>
  </NuxtErrorBoundary>
</template>
```

:LinkExample{link="/examples/app/error-handling"}