Next.js 15.1 released with React 19 support, new APIs, ESLint 9 integration, and more

Next.js 15.1 has been released, introducing several enhancements and new features for the React framework. This update brings official support for React 19 in both Pages Router and App Router. Developers can expect improved error debugging, with enhanced developer experience (DX) and better source maps available for both browsers and terminals.

A notable addition is the new API that allows code execution after a response has finished streaming. In terms of authentication, experimental forbidden and unauthorized APIs have been introduced for more detailed error handling. The release also includes support for ESLint 9, increases the maximum cache tags to 128, and provides an option to disable the experimental CssChunkingPlugin. Furthermore, experimental CSS inlining support has been added, alongside various other improvements and bug fixes.