Middleware x Rewriting url without locale prefix returns 404

[youminkim]

Run next info (available from version 12.0.8 and up)

No response

What version of Next.js are you using?

12.0.7

What version of Node.js are you using?

v14.15.4

What browser are you using?

chrome

What operating system are you using?

macOS

How are you deploying your application?

vercel

Describe the Bug

While rewriting subdomain in middleware, page is not loaded based on locale prefix.

import { NextResponse } from 'next/server';

export function middleware(req, ev) {
    ...

    // rewrite
    if (
        !pathname.includes('.') && // exclude all files in the public folder
        !pathname.startsWith('/api') // exclude all API routes
    ) {
        return NextResponse.rewrite(`/a/${subdomain}`); // return 404 not found
    }

    return response;
}

I tried return NextResponse.rewrite("/en/a/support") instead. In this case, the first hit returns white screen. second hit returns proper page.

Note that /a/support page use getStaticProps and getStaticPaths with fallback=true.

Sharing next.config.js

const moduleExports = {
    ...
    i18n: {
        locales: ['en', 'id', 'es'],
        defaultLocale: 'en'
    }
    ...
}

Expected Behavior

return NextResponse.rewrite(/en/a/${subdomain}) should work

To Reproduce

i18n setting in next.config.js

prepare ISR page

In middleware, rewrite without locale preifx. e.g. return NextResponse.rewrite(/a/abc)

[balazsorban44]

This might have already been fixed in #31174. Could you verify by using npm i next@canary

[youminkim]

Thanks @balazsorban44
it works well after upgrading

[balazsorban44]

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