Next.js 15.4 is here: What’s new and what to expect

Next.js 15.4 marks a significant milestone with Turbopack passing all 8,302 integration tests for production builds, making it production-ready. The release includes practical improvements like onInvalidate callback for router.prefetch(), global-not-found pages, debug-prerender flag, and various bug fixes. Performance optimizations include improved static path generation and React Compiler integration. The update sets the stage for Next.js 16, which will promote Turbopack to beta status and introduce unified caching with cacheComponents. Upgrading is straightforward using the automated CLI tool or manual dependency updates.