nextjs - 💡(How to fix) Fix Middleware rewrites cause repeated RSC fetches for previously visited search-param URLs [1 comments, 2 participants]

Summary

When middleware rewrites a short URL to a deeper internal path and <Link prefetch={false}> is used, every search-param navigation triggers an RSC fetch to the server — even for previously visited URLs. The same URL with the same _rsc key is fetched repeatedly instead of being served from the client-side segment cache.

Reproduction

Repo: https://github.com/damusnet/next-middleware-rewrite-scroll-bug

Deployment: https://next-scroll-repro.vercel.app/

Steps:

1. Open the deployment, open DevTools Network tab
2. Click "Item 11" — observe one RSC fetch (?item=10&_rsc=1k7fz)
3. Click "Item 5" — observe one RSC fetch (?item=4&_rsc=...)
4. Click "Item 11" again — observe another RSC fetch for ?item=10&_rsc=1k7fz (identical to step 2)

Expected: step 4 should be served from the client-side segment cache with no network request.

Conditions:

1. Middleware rewrites a short URL to a deeper internal path (common in i18n/multi-tenant apps)
2. <Link prefetch={false} href="?param=value">
3. Deployed on Vercel (ISR) — does not reproduce on local next start

Setup:

• Middleware rewrites / to /en/r/123
• Page at app/[locale]/r/[id]/page.tsx with revalidate = 60 and generateStaticParams = () => []

Analysis

The navigation flow:

1. navigateImpl misses on the route cache (different search params = different key)
2. deprecated_requestOptimisticRouteCacheEntry succeeds — finds the base route
3. navigateUsingPrefetchedRouteTree is used (correct)
4. spawnDynamicRequests fires because dynamicRequestTree is non-null (the page segment diverges)
5. The RSC response data is written to the segment/BFCache
6. On the next navigation to the same URL, the segment cache lookup misses and a new fetch is triggered

The segment cache miss likely occurs because the middleware rewrite causes a varyPath mismatch between the write (which uses the server response's route tree) and the read (which uses the optimistic route tree). The optimistic tree is constructed from the hydrated route, while the server response includes the rewritten path segments, producing different cache keys.

Related

This is a sibling issue to the scroll bug fixed in #92172. Same middleware rewrite pattern, same repro app. The scroll bug was about scroll={false} being dropped during SERVER_PATCH retries. This issue is about the segment cache not being reusable across navigations.

Environment

• Next.js 16.2.0
• Vercel deployment
• App Router with middleware