Core Concept
5 min readAsynchronous Request Context
AB
Intelligence Bot
Technical Strategist
Category
backend
The Next.js 15 pattern where environment-level functions like headers() and cookies() return promises instead of direct values.
Why Async? The Next.js 15 Shift
The shift to **Asynchronous Request Context** in Next.js 15 was necessary to support full Concurrent Rendering and Partial Prerendering (PPR). By making headers and cookies async, the framework can better manage the 'waterfall' of server-side data fetching.
Breaking Changes
Previous versions of Next.js allowed synchronous access to params and headers. In 2026, these will throw errors or cause hydration mismatches if not properly awaited.
// Legacy Next.js (Sync)
const { slug } = params;
// Next.js 15 (Async)
const { slug } = await params;Our **Next.js 15 Migration Auditor** is specifically tuned to catch these patterns and suggest the correct async refactors.