What's new in Next.js 16

Four releases in a year

Click a release to see what it brings.

Changes that trip people up

Many examples online date from Next.js 13 to 15. If some code won't compile, check these first. Toggle to compare.

middleware.ts becomes proxy.ts

// middleware.ts (Next.js 15)
import { NextResponse, type NextRequest } from 'next/server';

export function middleware(request: NextRequest) {
  return NextResponse.redirect(new URL('/fr', request.url));
}

// proxy.ts (Next.js 16): same logic, Node.js runtime
import { NextResponse, type NextRequest } from 'next/server';

export default function proxy(request: NextRequest) {
  return NextResponse.redirect(new URL('/fr', request.url));
}

params and cookies are async

// Next.js 14: params were a plain object
export default function Page({ params }: { params: { id: string } }) {
  const invoice = getInvoice(params.id);
  const theme = cookies().get('theme');
}

// Next.js 16: params, searchParams, cookies(), headers() are async
export default async function Page({ params }: PageProps<'/[locale]/invoices/[id]'>) {
  const { id } = await params;
  const theme = (await cookies()).get('theme');
}

revalidateTag takes a profile

revalidateTag('invoices');

revalidateTag('invoices', 'max'); // stale-while-revalidate
updateTag('invoices');            // Server Actions: read your own writes

• Node.js 20.9 and TypeScript 5.1 minimum.
• next lint is gone: run eslint directly, and next build no longer lints.
• Parallel routes require a default.tsx file for every slot.
• next/image: local images with a query string need images.localPatterns, and images.domains is deprecated in favor of remotePatterns.

Local error boundaries

Since 16.3, catchError creates an error boundary around a single block. Its retry() also refetches Server Components, and it lets notFound() and redirect() through.

'use client';

import { catchError, type ErrorInfo } from 'next/error';
import { useTranslations } from 'next-intl';

function InvoicesError(_props: object, { retry }: ErrorInfo) {
  const t = useTranslations('common.errors');
  return (
    <div role="alert">
      <p>{t('loadFailed')}</p>
      <button type="button" onClick={() => retry()}>{t('retry')}</button>
    </div>
  );
}

export default catchError(InvoicesError);

Everyday tooling

For server-side debugging, bundle size analysis and project upgrades.

next dev --inspect            # attach the Node.js debugger (16.1)
next start --inspect          # same in production (16.2)
next experimental-analyze     # bundle analyzer for Turbopack (16.1)

npx next upgrade                              # Next.js 16.1+
npx @next/codemod@canary upgrade latest       # from 15: async APIs, proxy, lint...
npx @next/codemod@canary next-lint-to-eslint-cli .  # next lint was removed

Sources: official Next.js blog (16, 16.1, 16.2 and 16.3 posts), checked in September 2026.