Middleware (12.2.3) causing infinite redirect/refresh of interior page routes

Verify canary release

• I verified that the issue exists in the latest Next.js canary release

Provide environment information

Operating System: Platform: linux Arch: x64 Version: #1 SMP Wed Mar 2 00:30:59 UTC 2022 Binaries: Node: 16.15.0 npm: 8.5.5 Yarn: 1.22.19 pnpm: 7.5.0 Relevant packages: next: 12.2.3 eslint-config-next: 12.2.3 react: 18.2.0 react-dom: 18.2.0

What browser are you using? (if relevant)

Firefox

How are you deploying your application? (if relevant)

Vercel

Describe the Bug

Since Middleware 12.2 stable, I have had issues with redirects happening infinitely for interior page routes (home path is fine). I have tried to strip away everything and I still get infinite redirects with just only the cookie setting option.

https://user-images.githubusercontent.com/222170/180466999-7ef7e685-958e-4a2a-a847-6ab0a2265853.mp4

Here is my middleware file in case any of you sleuths spot an error on my end:

import isbot from "isbot";
import { type NextRequest, NextResponse, userAgent } from "next/server";
import {
  fetchFeatureFlag,
  MarketingHomeAbTestVariantValues,
} from "src/api/fetchFeatureFlag";
import { Environments } from "src/interfaces/common.interfaces";
import { CONSTANTS } from "src/utils/constants";
import { v4 as uuid } from "uuid";

const PUBLIC_FILE = /\.(.*)$/;

isbot.extend(["/DatadogSynthetics/"]);

export async function middleware(request: NextRequest) {
  const nextPage = NextResponse.next();

  const { url } = request;
  const { ua } = userAgent(request);
  const { pathname, basePath, origin, locale, search } = request.nextUrl;
  const homeUrl = new URL(`${basePath}/`, origin).toString();
  const expires = new Date(Date.now() + 2592000000); // one month expiration

  if (
    pathname.startsWith("/_next") || // exclude Next.js internals
    pathname.startsWith("/api") || //  exclude all API routes
    pathname.startsWith("/static") || // exclude static files
    PUBLIC_FILE.test(pathname) // exclude all files in the public folder
  ) {
    return nextPage;
  }

  // Setup rhFeatureFlagUserId
  // this will run on all paths of the site, no matter
  // where a visitor enters, to ensure it gets set up
  let rhFeatureFlagUserId = request.cookies.get(
    CONSTANTS.RH_FEATURE_FLAG_USER_ID_COOKIE
  );

  if (!rhFeatureFlagUserId) {
    rhFeatureFlagUserId = `rh_${uuid()}`;

    nextPage.cookies.set(
      CONSTANTS.RH_FEATURE_FLAG_USER_ID_COOKIE,
      rhFeatureFlagUserId,
      {
        expires,
        sameSite: "strict",
      }
    );
  }

  // If pathname is not lowercase, redirect
  if (pathname !== pathname.toLowerCase()) {
    const lowercaseRedirect = NextResponse.redirect(
      new URL(`${pathname.toLowerCase()}${search}`, url)
    );

    lowercaseRedirect.cookies.set(
      CONSTANTS.RH_FEATURE_FLAG_USER_ID_COOKIE,
      rhFeatureFlagUserId,
      {
        expires,
        sameSite: "strict",
      }
    );

    return lowercaseRedirect;
  }

  // Redirect any direct traffic to our test variant back to home page
  if (
    process.env.ENVIRONMENT === Environments.Production &&
    pathname.startsWith("/variant-home")
  ) {
    const redirect = NextResponse.redirect(homeUrl);

    redirect.cookies.set(
      CONSTANTS.RH_FEATURE_FLAG_USER_ID_COOKIE,
      rhFeatureFlagUserId,
      {
        expires,
        sameSite: "strict",
      }
    );

    return redirect;
  }

  // Homepage AB Test Setup
  if (pathname === CONSTANTS.HOME_ROUTE && !isbot(ua)) {
    // Launch Darkly flag: marketing-home-ab-test-multiple-variants
    // If flag is off, defaults to "original" (control home page)
    const marketingHomeAbTestVariantSlug = await fetchFeatureFlag<string>({
      featureFlagUserId: rhFeatureFlagUserId,
      flag: "marketing-home-ab-test-multiple-variants",
      defaultValue: MarketingHomeAbTestVariantValues.Original,
    });

    if (marketingHomeAbTestVariantSlug) {
      const testPage =
        marketingHomeAbTestVariantSlug !==
        MarketingHomeAbTestVariantValues.Original
          ? NextResponse.rewrite(
              new URL(
                `${basePath}/${locale}/${marketingHomeAbTestVariantSlug}${search}`,
                origin
              ).toString()
            )
          : NextResponse.next();

      // Make sure we add our feature flag user id to cookies
      // since we reset the NextResponse to a new const
      testPage.cookies.set(
        CONSTANTS.RH_FEATURE_FLAG_USER_ID_COOKIE,
        rhFeatureFlagUserId,
        {
          expires,
          sameSite: "strict",
        }
      );

      testPage.cookies.set(
        CONSTANTS.RH_HOME_PAGE_TEST_COOKIE,
        marketingHomeAbTestVariantSlug,
        {
          expires,
          sameSite: "strict",
        }
      );

      return testPage;
    }

    return nextPage;
  }

  return nextPage;
}

Expected Behavior

12.1.6 nested middleware works fine (same setup is used there, just in 12.1.6 format https://www.gotrhythm.com). My expectations are that it should not cause an infinite redirect as you see in the video above with 12.2.3.

Link to reproduction

https://rhythm-marketing-l1rj1cudn-gotrhythm.vercel.app/

To Reproduce

Create a middleware file with a redirect.

[ludovicoserrani-nautes]

@ijjk I had the same issue as @wadehammes and it works for me in the latest canary 12.2.4-canary.8. Thank you!

[ijjk]

Circling back here this sounds related to https://github.com/vercel/next.js/issues/39049 which has been updated in v12.2.4-canary.3 of Next.js, please update and give it a try!