unauthorized) during prerender recovery #168

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opened 2026-05-06 12:37:49 +02:00 by BreizhHardware · 0 comments

BreizhHardware commented

2026-05-06 12:37:49 +02:00

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Originally created by @github-actions[bot] on GitHub (Apr 3, 2026).
Original GitHub issue: https://github.com/cloudflare/vinext/issues/764

Upstream change

Next.js PR #92231 (commit c06658e) fixes how notFound(), forbidden(), and unauthorized() errors are handled when they escape into the outer prerender recovery path.

Previously, when these errors escaped during prerendering (especially with cacheComponents), Next.js fell back to the generic error shell flow. This caused:

Error HTML rendered from ErrorApp instead of the correct fallback component
Flight data reused from the aborted prerender prelude with references to chunks that were never emitted
Client-side Connection closed failures

What changed

The fix introduces boundary-aware recovery for HTTP access errors during prerender:

findPrerenderHTTPErrorBoundaryTree — walks the loader tree to find the deepest segment that has a matching fallback boundary (not-found.tsx, forbidden.tsx, unauthorized.tsx)
When a boundary is found, the recovery path rerenders the normal app router RSC payload scoped to that boundary segment, instead of falling back to the generic error RSC payload
The replacement Flight stream is tee'd so Fizz can render from one copy while prerender buffering consumes the other
If no matching boundary exists, the existing generic error handling is preserved

Key files changed:

packages/next/src/server/app-render/app-render.tsx — prerender recovery path now checks for HTTP fallback boundaries
packages/next/src/server/app-render/create-component-tree.tsx — new PrerenderHTTPErrorState type, renders fallback element directly at the boundary segment instead of descending into the throwing subtree

Relevance to vinext

vinext implements its own App Router prerender/SSR path in entries/app-rsc-entry.ts and server/ modules. When notFound(), forbidden(), or unauthorized() is thrown during rendering, vinext needs to:

Find the deepest matching fallback boundary in the route tree (not-found.tsx / forbidden.tsx / unauthorized.tsx)
Rerender the RSC payload scoped to that boundary instead of falling back to a generic error shell
Ensure the Flight stream and HTML stream stay consistent (no dangling chunk references)

Without this fix, apps using notFound() inside layouts with Suspense boundaries may see client-side hydration errors or Connection closed failures.

Fixes upstream: vercel/next.js#86251, vercel/next.js#90837

Originally created by @github-actions[bot] on GitHub (Apr 3, 2026). Original GitHub issue: https://github.com/cloudflare/vinext/issues/764 ## Upstream change Next.js PR [#92231](https://github.com/vercel/next.js/pull/92231) (commit [`c06658e`](https://github.com/vercel/next.js/commit/c06658e9199bccc10de1daf24cf7fe542c5ee13a)) fixes how `notFound()`, `forbidden()`, and `unauthorized()` errors are handled when they escape into the outer prerender recovery path. Previously, when these errors escaped during prerendering (especially with `cacheComponents`), Next.js fell back to the generic error shell flow. This caused: - Error HTML rendered from `ErrorApp` instead of the correct fallback component - Flight data reused from the aborted prerender prelude with references to chunks that were never emitted - Client-side `Connection closed` failures ## What changed The fix introduces boundary-aware recovery for HTTP access errors during prerender: 1. **`findPrerenderHTTPErrorBoundaryTree`** — walks the loader tree to find the deepest segment that has a matching fallback boundary (`not-found.tsx`, `forbidden.tsx`, `unauthorized.tsx`) 2. When a boundary is found, the recovery path rerenders the **normal** app router RSC payload scoped to that boundary segment, instead of falling back to the generic error RSC payload 3. The replacement Flight stream is tee'd so Fizz can render from one copy while prerender buffering consumes the other 4. If no matching boundary exists, the existing generic error handling is preserved Key files changed: - `packages/next/src/server/app-render/app-render.tsx` — prerender recovery path now checks for HTTP fallback boundaries - `packages/next/src/server/app-render/create-component-tree.tsx` — new `PrerenderHTTPErrorState` type, renders fallback element directly at the boundary segment instead of descending into the throwing subtree ## Relevance to vinext vinext implements its own App Router prerender/SSR path in `entries/app-rsc-entry.ts` and `server/` modules. When `notFound()`, `forbidden()`, or `unauthorized()` is thrown during rendering, vinext needs to: 1. Find the deepest matching fallback boundary in the route tree (not-found.tsx / forbidden.tsx / unauthorized.tsx) 2. Rerender the RSC payload scoped to that boundary instead of falling back to a generic error shell 3. Ensure the Flight stream and HTML stream stay consistent (no dangling chunk references) Without this fix, apps using `notFound()` inside layouts with Suspense boundaries may see client-side hydration errors or `Connection closed` failures. Fixes upstream: vercel/next.js#86251, vercel/next.js#90837