Middleware : NextAuth v5 + Next intl

[adilsonx]

Hi 👋,

I'm encountering issues when combining next-auth v5 with next-intl middleware in my Next.js application. While everything works perfectly in development mode, deploying the app results in internal server errors.

Problem Details:

Libraries Involved:

• next-auth v5
• next-intl

Deployment : Self host

Issue:

Combining next-auth v5 middleware with next-intl causes internal server errors upon deployment.
The application functions correctly in development mode but fails in the production build. On the other hand, if I use only one of the two middlewares, I have no problem at all in production.

Attempts to Resolve:

• Followed examples from next-auth v4 documentation, which are now outdated.
• Tried nesting middleware and handling routes conditionally.
• Ensured configurations align with the latest next-auth v5 standards.

Sample Middleware Implementation (not working, provoking an internal server error in production) :

import { auth } from "@/auth";
import createMiddleware from "next-intl/middleware";
import { routing } from "./i18n/routing";
import { NextRequest, NextResponse } from "next/server";

// Initialize i18n middleware
const i18nMiddleware = createMiddleware(routing);

// Combined middleware function
export default auth(async (req: NextRequest) => {
  const { nextUrl } = req;
  const defaultLocale = routing.locales[0];

  const pathLocale = nextUrl.pathname.split("/")[1];
  const locale = (routing.locales as readonly string[]).includes(pathLocale)
    ? pathLocale
    : defaultLocale;

  const isPublic = isPublicRoute(nextUrl.pathname, locale);

  if (isApiRoute(nextUrl.pathname)) {
    if (!req.auth) {
      return new NextResponse(null, { status: 401 });
    }
    return;
  }

  if (isPublic) {
    return i18nMiddleware(req);
  }

  if (!req.auth) {
    const loginUrl = new URL(`/${locale}/auth/login`, nextUrl.origin);
    return NextResponse.redirect(loginUrl);
  }

  return i18nMiddleware(req);
});

// Middleware Configuration
export const config = {
  matcher: ["/((?!api|_next|.*\\..*).*)", "/", "/(api|trpc)(.*)"],
};

Request:

Could you please assist in resolving the compatibility issues between next-auth v5 and next-intl middleware? Any guidance or updated examples for integrating these two libraries in the latest versions would be greatly appreciated.

Thank you!