Metadata duplication in <head> when using next-intl middleware with locale redirects #80658
Description
Link to the code that reproduces this issue
https://github.com/jjtsou/job-board
To Reproduce
To Reproduce
- Set up next-intl middleware for internationalization.
- Configure locale routing with redirects from / to /[locale].
- Export a generateMetadata function in a page component.
- Navigate from / to a locale path (e.g., /en).
- Inspect the HTML output in browser DevTools.
Example code
// middleware.ts
import createMiddleware from 'next-intl/middleware';
import { routing } from './src/i18n/routing';
export default createMiddleware(routing);
export const config = {
matcher: ['/', '/(en|el)/:path*']
};// src/i18n/routing.ts
export const routing = {
locales: ['en', 'el'],
defaultLocale: 'en',
localePrefixMode: 'always'
} as const;// app/[locale]/page.tsx
export async function generateMetadata({
params,
searchParams,
}: Props): Promise<Metadata> {
const { locale } = await params;
const t = await getTranslations({ locale, namespace: "meta" });
return {
title: t('title'),
description: t('description'),
openGraph: {
title: t('title'),
description: t('description'),
type: "website",
locale,
},
};
}Current vs. Expected behavior
Following the steps from the previous section, I expected the metadata to appear only once in the section when redirecting between routes. However, metadata tags (title, description, Open Graph, etc.) are duplicated in the HTML output after locale redirects.
<head>
<title>Job Board</title>
<meta name="description" content="Find jobs..." />
</head><head>
<title>Job Board</title>
<title>Job Board</title>
<meta name="description" content="Find jobs..." />
<meta name="description" content="Find jobs..." />
</head>Provide environment information
Operating System:
Platform: darwin
Arch: arm64
Version: Darwin Kernel Version 24.4.0
Binaries:
Node: 21.6.2
npm: 10.2.4
Yarn: N/A
pnpm: N/A
Relevant Packages:
next: 15.3.2
eslint-config-next: N/A
react: 19.1.0
react-dom: 19.1.0
typescript: 5.8.3
next-intl: 4.1.0
Next.js Config:
output: N/AWhich area(s) are affected? (Select all that apply)
Metadata, Middleware, Redirects
Which stage(s) are affected? (Select all that apply)
Vercel (Deployed)
Additional context
Additional context
- Issue does NOT occur with static metadata exports.
- Only happens with generateMetadata function during locale redirects.
- Metadata merging behavior seems inconsistent with documented behavior.
- The issue is reproducible on deployed (Vercel) environments.