nextjs - 💡(How to fix) Fix 16.2.6 regression: dev server silently exits (code 0) after first browser page load when using proxy.ts + --webpack

import type { NextConfig } from "next";
import path from "path";
import createMDX from "@next/mdx";

const withMDX = createMDX({});

const nextConfig: NextConfig = {
  pageExtensions: ["js", "jsx", "ts", "tsx", "md", "mdx"],
  turbopack: {
    root: path.resolve(__dirname),
  },
};

export default withMDX(nextConfig);

---

import NextAuth from 'next-auth';
import { authConfig } from './auth.config';
import { NextResponse } from 'next/server';

const { auth } = NextAuth(authConfig);

export default auth((req) => {
  const { nextUrl } = req;
  const isAuthed = !!req.auth && !(req.auth as { error?: string }).error;

  if (!isAuthed) {
    if (nextUrl.pathname.startsWith('/api/')) {
      return NextResponse.json({ error: 'unauthenticated' }, { status: 401 });
    }
    const callbackUrl = encodeURIComponent(nextUrl.pathname + nextUrl.search);
    return NextResponse.redirect(
      new URL(`/signin?callbackUrl=${callbackUrl}`, nextUrl.origin),
    );
  }
});

export const config = {
  matcher: [
    '/((?!signin|api/auth|api/mcp|_next/static|_next/image|favicon.ico).*)',
  ],
};

---

▲ Next.js 16.2.6 (webpack)
✓ Ready in 153ms
○ Compiling / ...
 GET / 200 in 7.8s (next.js: 7.2s, proxy.ts: 113ms, application-code: 503ms)
[process exits with code 0 — no error, no stack trace]

---

Failed to load resource: net::ERR_EMPTY_RESPONSE @ /api/auth/session
ClientFetchError: Failed to fetch (next-auth)
Failed to load resource: net::ERR_EMPTY_RESPONSE @ /?_rsc=...
Failed to fetch RSC payload for http://localhost:3000/. Falling back to browser navigation.
Failed to load resource: net::ERR_SOCKET_NOT_CONNECTED @ ...