Nuxt/docs/1.getting-started/8.error-handling.md
2024-02-21 18:09:45 +01:00

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---
title: 'Error Handling'
description: 'Learn how to catch and handle errors in Nuxt.'
navigation.icon: i-ph-bug-beetle-duotone
---
Nuxt 3 is a full-stack framework, which means there are several sources of unpreventable user runtime errors that can happen in different contexts:
- Errors during the Vue rendering lifecycle (SSR & CSR)
- Errors during Nitro server lifecycle ([`server/`](/docs/guide/directory-structure/server) directory)
- Server and client startup errors (SSR + CSR)
- Errors downloading JS chunks
::tip
**SSR** stands for **Server-Side Rendering** and **CSR** for **Client-Side Rendering**.
::
## Vue Rendering Lifecycle
You can hook into Vue errors using [`onErrorCaptured`](https://vuejs.org/api/composition-api-lifecycle.html#onerrorcaptured).
In addition, Nuxt provides a [`vue:error`](/docs/api/advanced/hooks#app-hooks-runtime) 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.
```ts twoslash [plugins/error-handler.ts]
export default defineNuxtPlugin((nuxtApp) => {
nuxtApp.vueApp.config.errorHandler = (error, instance, info) => {
// handle error, e.g. report to a service
}
// Also possible
nuxtApp.hook('vue:error', (error, instance, info) => {
// handle error, e.g. report to a service
})
})
```
::note
Note that the `vue:error` hook is based on [`onErrorCaptured`](https://vuejs.org/api/composition-api-lifecycle.html#onerrorcaptured) lifecycle hook.
::
## Startup Errors
Nuxt will call the `app:error` hook if there are any errors in starting your Nuxt application.
This includes:
- running [Nuxt plugins](/docs/guide/directory-structure/plugins)
- processing `app:created` and `app:beforeMount` hooks
- rendering your Vue app to HTML (during SSR)
- mounting the app (on client-side), though you should handle this case with `onErrorCaptured` or with `vue:error`
- processing the `app:mounted` hook
## Nitro Server Lifecycle
You cannot currently define a server-side handler for these errors, but can render an error page, see the [Render an Error Page](#error-page) section.
## Errors with JS chunks
You might encounter chunk loading errors due to a network connectivity failure or a new deployment (which invalidates your old, hashed JS chunk URLs). Nuxt provides built-in support for handling chunk loading errors by performing a hard reload when a chunk fails to load during route navigation.
You can change this behavior by setting `experimental.emitRouteChunkError` to `false` (to disable hooking into these errors at all) or to `manual` if you want to handle them yourself. If you want to handle chunk loading errors manually, you can check out the [the automatic implementation](https://github.com/nuxt/nuxt/blob/main/packages/nuxt/src/app/plugins/chunk-reload.client.ts) for ideas.
## Error Page
::note
When Nuxt encounters a fatal error (any unhandled error on the server, or an error created with `fatal: true` on the client) it will either render a JSON response (if requested with `Accept: application/json` header) or trigger a full-screen error page.
::
An error may occur during the server lifecycle when:
- processing your Nuxt plugins
- rendering your Vue app into HTML
- a server API route throws an error
It can also occur on the client side when:
- processing your Nuxt plugins
- before mounting the application (`app:beforeMount` hook)
- mounting your app if the error was not handled with `onErrorCaptured` or `vue:error` hook
- the Vue app is initialized and mounted in browser (`app:mounted`).
::read-more{to="/docs/api/advanced/hooks"}
Discover all the Nuxt lifecycle hooks.
::
Customize the default error page by adding `~/error.vue` in the source directory of your application, alongside `app.vue`.
<!-- TODO:twoslash: Twoslash does not support tsconfig paths yet -->
```vue [error.vue]
<script setup lang="ts">
import type { NuxtError } from '#app'
const props = defineProps({
error: Object as () => NuxtError
})
const handleError = () => clearError({ redirect: '/' })
</script>
<template>
<div>
<h2>{{ error.statusCode }}</h2>
<button @click="handleError">Clear errors</button>
</div>
</template>
```
::read-more{to="/docs/guide/directory-structure/error"}
Read more about `error.vue` and its uses.
::
For custom errors we highly recommend to use `onErrorCaptured` composable that can be called in a page/component setup function or `vue:error` runtime nuxt hook that can be configured in a nuxt plugin.
```ts twoslash [plugins/error-handler.ts]
export default defineNuxtPlugin(nuxtApp => {
nuxtApp.hook('vue:error', (err) => {
//
})
})
```
When you are ready to remove the error page, you can call the [`clearError`](/docs/api/utils/clear-error) helper function, which takes an optional path to redirect to (for example, if you want to navigate to a 'safe' page).
::important
Make sure to check before using anything dependent on Nuxt plugins, such as `$route` or `useRouter`, as if a plugin threw an error, then it won't be re-run until you clear the error.
::
::note
If you are running on Node 16 and you set any cookies when rendering your error page, they will [overwrite cookies previously set](https://github.com/nuxt/nuxt/pull/20585). We recommend using a newer version of Node as Node 16 reached end-of-life in September 2023.
::
## Error Utils
### `useError`
```ts [TS Signature]
function useError (): Ref<Error | { url, statusCode, statusMessage, message, description, data }>
```
This function will return the global Nuxt error that is being handled.
::read-more{to="/docs/api/composables/use-error"}
Read more about `useError` composable.
::
### `createError`
```ts [TS Signature]
function createError (err: { cause, data, message, name, stack, statusCode, statusMessage, fatal }): Error
```
Create an error object with additional metadata. It is usable in both the Vue and Server portions of your app, and is meant to be thrown.
If you throw an error created with `createError`:
- on server-side, it will trigger a full-screen error page which you can clear with [`clearError`](#clearerror).
- on client-side, it will throw a non-fatal error for you to handle. If you need to trigger a full-screen error page, then you can do this by setting `fatal: true`.
```vue twoslash [pages/movies/[slug\\].vue]
<script setup lang="ts">
const route = useRoute()
const { data } = await useFetch(`/api/movies/${route.params.slug}`)
if (!data.value) {
throw createError({
statusCode: 404,
statusMessage: 'Page Not Found'
})
}
</script>
```
::read-more{to="/docs/api/utils/create-error"}
Read more about `createError` util.
::
### `showError`
```ts [TS Signature]
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`](#clearerror).
It is recommended instead to use `throw createError()`.
::read-more{to="/docs/api/utils/show-error"}
Read more about `showError` util.
::
### `clearError`
```ts [TS Signature]
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).
::read-more{to="/docs/api/utils/clear-error"}
Read more about `clearError` util.
::
## Render Error in Component
Nuxt also provides a [`<NuxtErrorBoundary>`](/docs/api/components/nuxt-error-boundary) 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.)
::tip
If you navigate to another route, the error will be cleared automatically.
::
```vue [pages/index.vue]
<template>
<!-- some content -->
<NuxtErrorBoundary @error="someErrorLogger">
<!-- You use the default slot to render your content -->
<template #error="{ error, clearError }">
You can display the error locally here: {{ error }}
<button @click="clearError">
This will clear the error.
</button>
</template>
</NuxtErrorBoundary>
</template>
```
:link-example{to="/docs/examples/advanced/error-handling"}