Experience with next/root-params / rootParams

[amannn]

With rootParams being available in the latest canary release of Next.js, I'd be curious how this feature is working for users of next-intl that have already decided to give it a shot!

My impression so far has been positive, these are my findings.

Bugs/missing:

• Client-side navigations within a given segment value will return undefined for the root param value if you have multiple root layouts (ref) Fixed in Next.js 15.2!
• I couldn't get global 404 pages to work (ref) → Should be fixed by [not-found] Add global-not-found convention vercel/next.js#78783 (comment)
• rootParams return an empty object in Route Handlers (fixed in feat: handle rootParams in routes (finish changes) vercel/next.js#81086)
• Not strictly an issue with rootParams, but dynamicParams = false might not trigger a 404 in production (generateStaticParams with dynamicParams false does not show not-found page on production vercel/next.js#54270)

Nice-to-have:

• Switching between root layouts causes a hard refresh (I think this is working as-designed)

Let me know if rootParams works well for your app!

Update: It seems like rootParams is renamed to next/root-params.

[sannajammeh]

This API does not work for me currently in 15 latest canary. It simply returns {} for every page its called in

[amannn]

Do you by chance have a layout at app/layout.tsx? If so, that would cause the empty object. You need to make sure that you only have layouts in nested folders like [locale].

[nevnein]

FYI this has been moved from unstable_rootParams to its own package(?), see https://github.com/vercel/next.js/releases/tag/v15.4.2-canary.42 and vercel/next.js#82582

[amannn]

Yep, unstable_rootParams will be replaced by next/root-params.

It's pretty much an equivalent for the previous API with one minor difference: Server Actions are (currently) not supported. AFAIK this is still under consideration and may change.

With Next.js 15.5, a deprecation notice for unstable_rootParams was added, but the API will continue to work until Next.js 16.

[GrahamQuan]

on next 15.5.0, current api can await a value, but any type

import { locale } from 'next/root-params';

const localeValue = await locale(); // `localeValue` type is any

i wonder how to add types in the future, locale() should be Promise<'en' | 'es' | ...>

[amannn]

I think it's coming: vercel/next.js#80618