MIGRATION: Async Request APIs

Purpose

Teach the breaking changes in Next.js 16 where request APIs are now async. This affects params, searchParams, cookies(), headers(), and draftMode() - all now return Promises and require await.

When to Use

• Migrating from Next.js 15 to 16
• Fixing TypeScript errors about Promise types
• Working with route parameters, search params, or request headers
• Encountering "object is possibly undefined" errors
• Updating Server Components or API routes

Breaking Changes Overview

APIs Now Async