redirect and notFound

In Server Components, Route Handlers and Server Actions, call redirect() from next/navigation. It stops rendering and sends the user elsewhere (it works by throwing a special error, so do not wrap it in try/catch).

app/account/page.tsx

import { redirect } from 'next/navigation';
import { getCurrentUser } from '@/lib/auth';

export default async function AccountPage() {
  const user = await getCurrentUser();
  if (!user) redirect('/login?next=/account');

  return <h1>Hello, {user.name}</h1>;
}

curl -i http://localhost:3000/account

HTTP/1.1 307 Temporary Redirect
location: /login?next=/account

notFound() renders the nearest not-found.tsx and returns HTTP 404. Use it when a product id does not exist.

import { notFound } from 'next/navigation';
import { getProduct } from '@/lib/products';

export default async function ProductPage({ params }: { params: Promise<{ id: string }> }) {
  const { id } = await params;
  const product = await getProduct(Number(id));
  if (!product) notFound();

  return <h1>{product.name}</h1>;
}

curl -i http://localhost:3000/products/99999

HTTP/1.1 404 Not Found
content-type: text/html; charset=utf-8