| |
| title: How to upgrade to version 12 |
| nav_title: Version 12 |
| description: Upgrade your Next.js Application from Version 11 to Version 12. |
| |
|
|
| To upgrade to version 12, run the following command: |
|
|
| ```bash filename="Terminal" |
| npm i next@12 react@17 react-dom@17 eslint-config-next@12 |
| ``` |
|
|
| ```bash filename="Terminal" |
| yarn add next@12 react@17 react-dom@17 eslint-config-next@12 |
| ``` |
|
|
| ```bash filename="Terminal" |
| pnpm up next@12 react@17 react-dom@17 eslint-config-next@12 |
| ``` |
|
|
| ```bash filename="Terminal" |
| bun add next@12 react@17 react-dom@17 eslint-config-next@12 |
| ``` |
|
|
| > **Good to know:** If you are using TypeScript, ensure you also upgrade `@types/react` and `@types/react-dom` to their corresponding versions. |
|
|
| ### Upgrading to 12.2 |
|
|
| [Middleware](/docs/messages/middleware-upgrade-guide) - If you were using Middleware prior to `12.2`, please see the [upgrade guide](/docs/messages/middleware-upgrade-guide) for more information. |
|
|
| ### Upgrading to 12.0 |
|
|
| [Minimum Node.js Version](https://nodejs.org/en/) - The minimum Node.js version has been bumped from `12.0.0` to `12.22.0` which is the first version of Node.js with native ES Modules support. |
|
|
| [Minimum React Version](https://react.dev/learn/add-react-to-an-existing-project) - The minimum required React version is `17.0.2`. To upgrade you can run the following command in the terminal: |
|
|
| ```bash filename="Terminal" |
| npm install react@latest react-dom@latest |
|
|
| yarn add react@latest react-dom@latest |
|
|
| pnpm update react@latest react-dom@latest |
|
|
| bun add react@latest react-dom@latest |
| ``` |
|
|
| #### SWC replacing Babel |
|
|
| Next.js now uses the Rust-based compiler [SWC](https://swc.rs/) to compile JavaScript/TypeScript. This new compiler is up to 17x faster than Babel when compiling individual files and up to 5x faster Fast Refresh. |
|
|
| Next.js provides full backward compatibility with applications that have [custom Babel configuration](/docs/pages/guides/babel). All transformations that Next.js handles by default like styled-jsx and tree-shaking of `getStaticProps` / `getStaticPaths` / `getServerSideProps` have been ported to Rust. |
|
|
| When an application has a custom Babel configuration, Next.js will automatically opt-out of using SWC for compiling JavaScript/Typescript and will fall back to using Babel in the same way that it was used in Next.js 11. |
|
|
| Many of the integrations with external libraries that currently require custom Babel transformations will be ported to Rust-based SWC transforms in the near future. These include but are not limited to: |
|
|
| - Styled Components |
| - Emotion |
| - Relay |
|
|
| In order to prioritize transforms that will help you adopt SWC, please provide your `.babelrc` on [this feedback thread](https://github.com/vercel/next.js/discussions/30174). |
|
|
| #### SWC replacing Terser for minification |
|
|
| You can opt-in to replacing Terser with SWC for minifying JavaScript up to 7x faster using a flag in `next.config.js`: |
|
|
| ```js filename="next.config.js" |
| module.exports = { |
| swcMinify: true, |
| } |
| ``` |
|
|
| Minification using SWC is an opt-in flag to ensure it can be tested against more real-world Next.js applications before it becomes the default in Next.js 12.1. If you have feedback about minification, please leave it on [this feedback thread](https://github.com/vercel/next.js/discussions/30237). |
|
|
| #### Improvements to styled-jsx CSS parsing |
|
|
| On top of the Rust-based compiler we've implemented a new CSS parser based on the one used for the styled-jsx Babel transform. This new parser has improved handling of CSS and now errors when invalid CSS is used that would previously slip through and cause unexpected behavior. |
| |
| Because of this change invalid CSS will throw an error during development and `next build`. This change only affects styled-jsx usage. |
| |
| #### `next/image` changed wrapping element |
| |
| `next/image` now renders the `<img>` inside a `<span>` instead of `<div>`. |
| |
| If your application has specific CSS targeting span such as `.container span`, upgrading to Next.js 12 might incorrectly match the wrapping element inside the `<Image>` component. You can avoid this by restricting the selector to a specific class such as `.container span.item` and updating the relevant component with that className, such as `<span className="item" />`. |
| |
| If your application has specific CSS targeting the `next/image` `<div>` tag, for example `.container div`, it may not match anymore. You can update the selector `.container span`, or preferably, add a new `<div className="wrapper">` wrapping the `<Image>` component and target that instead such as `.container .wrapper`. |
| |
| The `className` prop is unchanged and will still be passed to the underlying `<img>` element. |
| |
| See the [documentation](/docs/pages/api-reference/components/image#styling-images) for more info. |
| |
| #### HMR connection now uses a WebSocket |
| |
| Previously, Next.js used a [server-sent events](https://developer.mozilla.org/docs/Web/API/Server-sent_events) connection to receive HMR events. Next.js 12 now uses a WebSocket connection. |
| |
| In some cases when proxying requests to the Next.js dev server, you will need to ensure the upgrade request is handled correctly. For example, in `nginx` you would need to add the following configuration: |
| |
| ```nginx |
| location /_next/webpack-hmr { |
| proxy_pass http://localhost:3000/_next/webpack-hmr; |
| proxy_http_version 1.1; |
| proxy_set_header Upgrade $http_upgrade; |
| proxy_set_header Connection "upgrade"; |
| } |
| ``` |
| |
| If you are using Apache (2.x), you can add the following configuration to enable web sockets to the server. Review the port, host name and server names. |
| |
| ``` |
| <VirtualHost *:443> |
| # ServerName yourwebsite.local |
| ServerName "${WEBSITE_SERVER_NAME}" |
| ProxyPass / http://localhost:3000/ |
| ProxyPassReverse / http://localhost:3000/ |
| # Next.js 12 uses websocket |
| <Location /_next/webpack-hmr> |
| RewriteEngine On |
| RewriteCond %{QUERY_STRING} transport=websocket [NC] |
| RewriteCond %{HTTP:Upgrade} websocket [NC] |
| RewriteCond %{HTTP:Connection} upgrade [NC] |
| RewriteRule /(.*) ws://localhost:3000/_next/webpack-hmr/$1 [P,L] |
| ProxyPass ws://localhost:3000/_next/webpack-hmr retry=0 timeout=30 |
| ProxyPassReverse ws://localhost:3000/_next/webpack-hmr |
| </Location> |
| </VirtualHost> |
| ``` |
| |
| For custom servers, such as `express`, you may need to use `app.all` to ensure the request is passed correctly, for example: |
| |
| ```js |
| app.all('/_next/webpack-hmr', (req, res) => { |
| nextjsRequestHandler(req, res) |
| }) |
| ``` |
| |
| #### Webpack 4 support has been removed |
| |
| If you are already using webpack 5 you can skip this section. |
| |
| Next.js has adopted webpack 5 as the default for compilation in Next.js 11. As communicated in the [webpack 5 upgrading documentation](/docs/messages/webpack5) Next.js 12 removes support for webpack 4. |
| |
| If your application is still using webpack 4 using the opt-out flag, you will now see an error linking to the [webpack 5 upgrading documentation](/docs/messages/webpack5). |
| |
| #### `target` option deprecated |
| |
| If you do not have `target` in `next.config.js` you can skip this section. |
| |
| The target option has been deprecated in favor of built-in support for tracing what dependencies are needed to run a page. |
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| During `next build`, Next.js will automatically trace each page and its dependencies to determine all of the files that are needed for deploying a production version of your application. |
| |
| If you are currently using the `target` option set to `serverless`, please read the [documentation on how to leverage the new output](/docs/pages/api-reference/config/next-config-js/output). |
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