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CacheComponents: Client Navigation To GenerateStaticParams Path Crashes With React #412 When Custom CacheHandler Misses

When using Next.js 16.4.0 with cacheComponents and a custom cacheHandler that starts empty (e.g. Redis after eviction), a client-side navigation to a prerendered dynamic route (generateStaticParams) returns an unresumable fallback shell instead of rendering the page, causing React error #412. The issue originates from app-page-runtime.js marking non-prefetch RSC requests as static due to the presence of prefetchDataRoute, and then serving the fallback shell on a cache miss instead of dynamically rendering.

highConfidence 92%Next.js Affected V16.3.8 Affected V16.4.0 Affected V16.5.0-Canary.3

Origin Analysis

In app-page-runtime.js, isDynamicRSCRequest is computed as isRoutePPREnabled && isRSCRequest && !isPrefetchRSCRequest && !staticPrefetchDataRoute. For prerendered routes with a prefetchDataRoute, non-prefetch RSC navigation requests are incorrectly considered static. On a cache miss, the condition (nextConfig.cacheComponents ? !isDynamicRSCRequest : !isRSCRequest) evaluates to true, so the fallback shell is served with x-nextjs-postponed: 1. Since static RSC requests are never resumed, the Suspense child row is never sent, causing React error #412.

1. Clone repository from https://github.com/tdejager/next-cache-miss-fallback-shell-repro 2. Run pnpm install && pnpm exec playwright install chromium 3. Execute ./repro.sh (builds and runs next start twice: default cache and CUSTOM_CACHE=1) 4. In custom cache mode, open / and click the /items/a link 5. Observe that the Suspense fallback appears and then the error boundary shows Minified React error #412

Fixing Code Block

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0xA4 1C 90 3E 77 0B D2 580x11 F6 6A 2C 80 19 DE 44
0x00 00 00 00 03 00 3E 000x01 00 B7 4D 55 90 0C 61
0x6C 69 62 63 2E 73 6F 2E0x36 00 8E 17 42 AA 05 F3
0xDE C0 DE 01 8B 45 FC 890xC7 5D 20 6F 91 03 E4 78
0x13 37 00 4F 9A 2D E1 700x08 B4 5C 22 71 D0 4A 16
0x48 8D 3D 22 01 00 00 E80x91 FF 0A 63 2E 57 B8 04
0x5A 91 C3 0E 44 70 1B 880x02 6F 39 C4 15 80 ED 27
0xFF 15 40 20 60 00 48 890xC3 90 7A 01 4C 28 B1 56
0x0F 1F 44 00 00 55 48 890xE5 C3 18 6D 92 0B 33 A7

Edge Case Audit

This change may cause more requests to be treated as dynamic in cacheComponents mode, potentially increasing server load and altering caching behavior. It should be thoroughly tested with PPR, static export, prefetch, and cache-hit scenarios. Rollback: revert the expression to the original form. Note that this hotfix only addresses the symptom and may not cover all edge cases; monitor for regressions in related navigation flows.