nextjs - 💡(How to fix) Fix NextResponse.rewrite() breaks after first HMR update in dev (proxy/middleware edge runtime) [1 comments, 2 participants]

Link to the code that reproduces this issue

https://github.com/vercel/next.js/discussions

To Reproduce

1. Create a proxy.ts (or middleware.ts in older versions) that rewrites a path:

import { NextRequest, NextResponse } from "next/server";

export async function proxy(request: NextRequest) {
  const pathname = request.nextUrl.pathname;

  if (pathname.startsWith("/rewrite-me")) {
    const newPath = pathname.replace("/rewrite-me", "/api/target");
    return NextResponse.rewrite(new URL(newPath, request.url));
  }

  return NextResponse.next();
}

export const config = {
  matcher: ["/rewrite-me/:path*"],
};

1. Run next dev --turbopack (also reproduces without --turbopack, using webpack)
2. Make a request to /rewrite-me — works correctly
3. Edit any file to trigger HMR
4. Make the same request to /rewrite-me — 500 Internal Server Error

Current vs. Expected behavior

Current: After HMR invalidates the edge runtime module, NextResponse.rewrite() returns a NextResponse instance that fails Next.js's internal response instanceof Response check. The rewrite silently fails and the request falls through to a 500.

On the first request after a fresh server start, response instanceof Response is true. After HMR triggers, the same code path returns false because the Response class used by NextResponse and the one used by the runtime's instanceof check are now different objects (different module evaluation contexts).

Expected: NextResponse.rewrite() should work consistently across HMR cycles in dev mode.

Workaround

Using a plain Response with the internal x-middleware-rewrite header (which is what NextResponse.rewrite() does under the hood) avoids the class identity mismatch:

const newUrl = new URL(newPath, request.url);
return new Response(null, {
  headers: { "x-middleware-rewrite": newUrl.href },
});

This works because new Response() uses the global Response constructor rather than the one captured in the NextResponse module scope.

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin 25.3.0

Binaries:
  Node: 22.14.0
  npm: 10.9.2

Relevant Packages:
  next: 16.1.6
  react: 19.1.0
  react-dom: 19.1.0

Which area(s) are affected? (Select all that apply)

Middleware / Proxy (Routing)

Which stage(s) are affected? (Select all that apply)

next dev (local)

Additional context

• Reproduces with both --turbopack and webpack dev server
• Does not affect production builds — only dev mode with HMR
• The root cause appears to be that HMR re-evaluates the edge runtime module containing Response/NextResponse, but the instanceof check elsewhere uses the original class reference from before the reload