Next.js: Cache Fixes and Performance Updates

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Good morning. This is your Next.js development briefing for May 27th, 2026.

Twenty pull requests were merged yesterday, focusing on cache reliability and browser compatibility improvements.

Andrew Clark merged a critical bugfix for incorrect search params stored in cache. The route cache was incorrectly keying entries, causing stale search strings to appear in browser address bars after navigation. This resolves reported issues with router.push and router.replace operations.

Josh Story merged improvements to notFound recovery in error pathways, effectively relanding previous changes that handle cache components behavior when pages call notFound. This addresses connection closed problems during static prerendering.

The team also addressed a Firefox-specific issue. An update fixed refresh loops on initial load of streaming pages in development mode, where Firefox's transferSize property behavior was causing incorrect cache restore detection.

Tobias Koppers merged a significant Turbopack fix addressing an unsound IntoIterator implementation for ReadRef, which was causing use-after-free panics during JSON serialization. This required updates across 29 files to ensure memory safety.

React dependencies were upgraded from d5736f09 to 75b0945b, incorporating the latest upstream changes across 70 files.

Andrew Clark also introduced client-side App Shell prefetching behind the experimental.appShells flag. This allows instant navigation to route shells while param-specific content loads in the background.

Additional updates include Pages Router export file improvements, GitHub Actions security hardening, and enhanced error overlay pagination in the development interface.

What's next: App Shell prefetching for static routes and continued cache component optimizations are in development.

That's your Next.js briefing. Stay tuned for tomorrow's updates.