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NoFallbackError on 404 routes with pages router and middleware. #69786

Closed atissedrescaleway closed 1 month ago

atissedrescaleway commented 1 month ago

Link to the code that reproduces this issue

TBD

To Reproduce

We are using a self hosted version of Next.js with the pages router in version 14.2.7.

Important note: we are using the following middleware.ts which was the "unofficial" solution suggested by @leerob so be able to have a prefix in the URL for the default locale.

middleware.ts

import type { NextRequest } from 'next/server';
import { NextResponse } from 'next/server';

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

// This middleware is necessary to have a prefix for the default locale /en/ : https://nextjs.org/docs/pages/building-your-application/routing/internationalization#prefixing-the-default-locale
export function middleware(req: NextRequest) {
  if (
    req.nextUrl.pathname.startsWith('/_next') ||
    req.nextUrl.pathname.includes('/api/') ||
    PUBLIC_FILE.test(req.nextUrl.pathname)
  ) {
    return;
  }

  if (req.nextUrl.locale === 'default') {
    const locale = req.cookies.get('NEXT_LOCALE')?.value || 'en';

    NextResponse.redirect(
      new URL(
        `/${locale}${req.nextUrl.pathname}${req.nextUrl.search}`,
        req.url,
      ),
    );
  }
}

Current vs. Expected behavior

Current:

Expected:

Details :

Since we updated the Next.js from version 14.2.5 to 14.2.7, we observed a significant number of 500 errors with the code "NoFallbackError" in production.

This is the log from the Next.js server when visiting a route that doesn't exist:

NoFallbackError at cacheEntry.responseCache.get.routeKind (//node_modules/next/dist/server/base-server.js:1547:27) at process.processTicksAndRejections (node:internal/process/task_queues:95:5) at async /next-website/node_modules/next/dist/server/response-cache/index.js:90:36 at async /next-website/node_modules/next/dist/lib/batcher.js:45:32


When downgrading to 14.2.6, **our app is working correctly**.

### Provide environment information

```bash
Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 23.5.0: Wed May  1 20:14:38 PDT 2024; root:xnu-10063.121.3~5/RELEASE_ARM64_T6020
  Available memory (MB): 16384
  Available CPU cores: 10
Binaries:
  Node: 20.11.1
  npm: 10.2.4
  Yarn: 3.8.3
  pnpm: 9.1.3
Relevant Packages:
  next: 14.2.7 // There is a newer version (14.2.8) available, upgrade recommended! 
  eslint-config-next: 14.1.1
  react: 18.3.1
  react-dom: 18.3.1
  typescript: 5.5.3
Next.js Config:
  output: standalone

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

Internationalization (i18n), Middleware, Pages Router

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

next dev (local), next start (local), Other (Deployed)

Additional context

So my guess is that this bug is related to this commit, which was released in the v14.2.7 and affects the middleware code : https://github.com/vercel/next.js/pull/67734

github-actions[bot] commented 1 month ago

We could not detect a valid reproduction link. Make sure to follow the bug report template carefully.

Why was this issue closed?

To be able to investigate, we need access to a reproduction to identify what triggered the issue. We need a link to a public GitHub repository (template for App Router, template for Pages Router), but you can also use these templates: CodeSandbox: App Router or CodeSandbox: Pages Router.

The bug template that you filled out has a section called "Link to the code that reproduces this issue", which is where you should provide the link to the reproduction.

What should I do?

Depending on the reason the issue was closed, you can do the following:

In general, assume that we should not go through a lengthy onboarding process at your company code only to be able to verify an issue.

My repository is private and cannot make it public

In most cases, a private repo will not be a sufficient minimal reproduction, as this codebase might contain a lot of unrelated parts that would make our investigation take longer. Please do not make it public. Instead, create a new repository using the templates above, adding the relevant code to reproduce the issue. Common things to look out for:

I did not open this issue, but it is relevant to me, what can I do to help?

Anyone experiencing the same issue is welcome to provide a minimal reproduction following the above steps by opening a new issue.

I think my reproduction is good enough, why aren't you looking into it quickly?

We look into every Next.js issue and constantly monitor open issues for new comments.

However, sometimes we might miss one or two due to the popularity/high traffic of the repository. We apologize, and kindly ask you to refrain from tagging core maintainers, as that will usually not result in increased priority.

Upvoting issues to show your interest will help us prioritize and address them as quickly as possible. That said, every issue is important to us, and if an issue gets closed by accident, we encourage you to open a new one linking to the old issue and we will look into it.

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