when redirect in next.config broken manifest

[FrontLeejonghun]

Description

Subject: Manifest error occurs when redirecting in next-intl environment

Currently, our product does not have a root index page, and certain pages are accessed via redirects configured in next.config. In our testbed project, this is the /outer/inner page.

When performing a redirect, a manifest error occurs:
No content available because this request was redirected

Additionally, although this issue does not reproduce in all projects, the following error can occur:

Manifest fetch from 
http://localhost:3002/manifest.webmanifest/outer/inner failed, code 404

Upon closer inspection, the error is caused by:

http://localhost:3002/manifest.webmanifest 308 redirect  
-> http://localhost:3002/manifest.webmanifest/outer/inner failed, code 404

We are not certain whether this is a next-intl issue or a bug in Next.js itself. However, it appears to occur only when using the next-intl environment. Please note that in a create-next-app setup, this works correctly (possibly because the locale folder is missing).

If this is not an issue with next-intl, we apologize in advance.
We look forward to your guidance.

Verifications

• I've verified that the problem I'm experiencing isn't covered in the docs.
• I've searched for similar, existing issues on GitHub and Stack Overflow.
• I've compared my app to a working example to look for differences.

Mandatory reproduction URL

https://github.com/FrontLeejonghun/next-intl-test

Reproduction description

Open the reproduction project.
Access the /outer/inner page via redirect configured in next.config.
Observe the manifest error: No content available because this request was redirected.

Expected behaviour

When accessing a page via redirect in next-intl, the manifest should load correctly without any redirect or 404 errors. The request to manifest.webmanifest should return the valid manifest content regardless of the redirected URL.

[amannn]

Your redirect pattern with source: '/:locale' is likely too aggressive and catches e.g. the manifest request.

You might need something more explicit like this:

// next.config.ts

import createNextIntlPlugin from 'next-intl/plugin';
import {routing} from './src/i18n/routing';

const withNextIntl = createNextIntlPlugin();

/** @type {import('next').NextConfig} */
const nextConfig = {
  async redirects() {
    return [
      ...routing.locales.flatMap((locale) => [
        {
          source: `/${locale}`,
          destination: `/${locale}/outer/inner`,
          permanent: true
        },
        {
          source: `/${locale}/outer`,
          destination: `/${locale}/outer/inner`,
          permanent: true
        }
      ])
    ];
  }
};

export default withNextIntl(nextConfig);

I'll move this to a discussion since it seems to be a usage question.