Affected version
Reports that share this version, grouped in one feed.
When a route with dynamicParams:false calls notFound(), it returns 200 with not-found UI if a root loading.tsx and a sibling dynamicParams:true route exist. The 404 status is lost during streaming; the incremental cache stores a 200 response.
When a slow RSC fetch for a route fails after the user has navigated to another page via client-side navigation, Next.js incorrectly performs a full page load to the abandoned route's URL, disrupting the user experience.
In Next.js App Router, when a `useServerInsertedHTML` callback returns an empty Fragment (or null, empty array), the server still performs an additional React render for each streamed chunk because the callback result is always wrapped in a keyed Fragment, preventing the existing empty-result optimization in `getServerInsertedHTML()`. This leads to significant performance overhead in streaming scenarios with many Suspense boundaries.
SharedCacheControls stores cache-control metadata for every ISR path in a static Map without any eviction or bound, causing heap memory to grow without limit in production next start servers that generate many distinct ISR paths.
In Next.js Pages Router, calling res.revalidate('/') after a content publish can return success while the next request still serves the pre-publish version. This occurs when a normal background ISR render is already in-flight and reads data before publication; the on-demand revalidation reuses that in-flight render, and the stale result is persisted with a fresh cache timestamp.
Next.js 16.3 introduced a regression where route handler modules are not eagerly evaluated at startup, causing the first request to a route handler to pay full module evaluation cost. This increases cold start latency and p99 for deployments.
Editing a server component before the page finishes hydrating triggers a React warning ('Can't perform a React state update on a component that hasn't mounted yet') and can lead to a hydration mismatch. The issue occurs only in Next.js dev mode with HMR active, both Turbopack and webpack.