rsnext/errors/webpack5.md

Webpack 5 Adoption

Why This Message Occurred

Next.js will soon adopt webpack 5 as the default for compilation. We've spent a lot of effort into ensuring the transition from webpack 4 to 5 will be as smooth as possible. For example Next.js now comes with both webpack 4 and 5 allowing you to adopt webpack 5 by adding a flag to your next.config.js:

module.exports = {
  future: {
    webpack5: true,
  },
}

Adopting webpack 5 in your application has many benefits, notably:

• Improved Disk Caching: next build is significantly faster on subsequent builds
• Improved Fast Refresh: Fast Refresh work is prioritized
• Improved Long Term Caching of Assets: Deterministic code output that is less likely to change between builds
• Improved Tree Shaking
• Support for assets using new URL("file.png", import.meta.url)
• Support for web workers using new Worker(new URL("worker.js", import.meta.url))
• Support for exports/imports field in package.json

In upcoming releases we'll gradually roll out webpack 5 to applications that are compatible with webpack 5:

• In the next minor version we'll automatically opt-in applications without custom webpack configuration in next.config.js
• In the next minor version we'll automatically opt-in applications that do not have a next.config.js
• In the next major version we'll enable webpack 5 by default. You'll still be able to opt-out and use webpack 4 to help with backwards compatibility

Custom webpack configuration

In case you do have custom webpack configuration, either through custom plugins or your own modifications you'll have to take a few steps to ensure your applications works with webpack 5.

• When using next-transpile-modules make sure you use the latest version which includes this patch
• When using @zeit/next-css / @zeit/next-sass make sure you use the built-in CSS/Sass support instead
• When using @zeit/next-preact use this example instead
• When using @zeit/next-source-maps use the built-in production Source Map support
• When using webpack plugins make sure they're upgraded to the latest version, in most cases the latest version will include webpack 5 support. In some cases these upgraded webpack plugins will only support webpack 5.

Useful Links

In case you're running into issues you can connect with the community in this help discussion.