renderHTTPAccessFallbackPage does not pass params to layout components

[Jbithell]

renderHTTPAccessFallbackPage does not pass params to layout components

---

When vinext renders HTTP access fallback pages (404, 403, 401), layout components are rendered without the params prop, causing layouts that destructure route params to crash with:

Cannot destructure property 'lang' of '(intermediate value)' as it is undefined.

Root cause

In the bundled output, renderHTTPAccessFallbackPage creates layout elements with only { children } and no params:

// renderHTTPAccessFallbackPage path — no params passed
const LayoutComponent = layouts[i3]?.default;
if (LayoutComponent) {
  element = createElement(LayoutComponent, { children: element });
}

The normal render path correctly passes params:

// normal render path — params passed correctly
const layoutProps = { children: element, params: makeThenableParams(params) };

This affects both the RSC and non-RSC branches within renderHTTPAccessFallbackPage.

Reproduction

1. Create a Next.js app with a dynamic [lang] route segment
2. In app/[lang]/layout.tsx, destructure lang from params:

export default async function RootLayout({
  params,
  children,
}: {
  params: Promise<{ lang: string }>;
  children: React.ReactNode;
}) {
  const { lang } = await params;
  // use lang...
}

3. Navigate to any URL that triggers a 404 (e.g. /en/nonexistent-page)
4. The layout crashes because params is undefined

Expected behavior

renderHTTPAccessFallbackPage should pass params: makeThenableParams(params) to layout components, matching the normal render path.

Workaround

Add nullish coalescing when destructuring params in layouts:

const { lang } = (await params) ?? {};

Environment

• vinext: ^0.0.22
• next: 15.5.2

[james-elicx]

I've had the fix for this sat in the big batch of fixes i made for another project. Slowly sifting through them this weekend and trying to make repros for each one before merging...