Next.js 15 RC Now Available

The Next.js 15 Release Candidate (RC) is out, providing early access to new features and improvements before the stable release.

The BIG update is that this version supports React 19 RC introduces several experimental features, and updates existing functionalities.

React 19 RC and New Compiler

Next.js 15 RC supports React 19 RC, bringing new client and server features. It also introduces the experimental React Compiler, which optimizes code by reducing the need for manual memoization, making code simpler and less error-prone. Developers can enable this by installing babel-plugin-react-compiler and configuring it in next.config.js.

// next.config.js
const nextConfig = {
  experimental: {
    reactCompiler: true,
  },
};
 
module.exports = nextConfig;

Improved Hydration Error Messages

Next.js 15 improves hydration error views, providing clearer error messages with source code and suggestions for fixes.

Caching Updates

Default caching behaviors have been revised. 🎉

The community definitely requested this because of the confusion often caused by the default Fetch requests being cached. These are now uncached by default, enhancing performance and compatibility with features like Partial Prerendering (PPR).

## Partial Prerendering (Experimental) PPR allows combining static and dynamic rendering on the same page. In Next.js 15, developers can incrementally adopt PPR by setting specific layouts and pages to use it, aiming for full app adoption eventually.

next/after API (Experimental)

The new next/after API allows executing code after a response has finished streaming, useful for non-critical tasks like logging and analytics, without delaying the user response.

create-next-app Updates

create-next-app has a new design and includes prompts for enabling Turbopack during local development. A new --empty flag has also been added to simplify starting new projects.

## Optimized Bundling of External Packages Next.js 15 introduces new configuration options for bundling external packages, improving cold start performance. The App Router now bundles external packages by default, and the Pages Router has a new bundlePagesRouterDependencies option for similar functionality.

Get Started

To try Next.js 15 RC, use the following command:

npm install next@rc react@rc react-dom@rc

Documentation is available at rc.nextjs.org/docs until the stable release.