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Scroll-To-Top Lost On Navigation When Root Parallel-Slot Catch-All Sits Next To Sibling Dynamic Segment (Next.Js 16.3+ Optimistic Routing Regression)

In Next.js 16.3.0 and later with optimisticRouting enabled by default, navigation from a dynamic segment to another dynamic route can fail to reset scroll position. This occurs when the app has a root parallel slot with a catch-all page returning null, alongside a sibling dynamic route. Predicted route trees reify stale params, causing a server mismatch and retry that consumes the scroll-ref on an empty catch-all leaf, so the new page retains the previous scroll offset.

highConfidence 92%Next.js Affected V16.3.0 Affected V16.3.1 Affected V16.3.2 Affected V16.3.3 Affected V16.4.0-Canary.10

Origin Analysis

The optimistic routing feature introduced in 16.3.0 predicts known-route trees. When a root parallel slot's catch-all page sits next to a dynamic segment, the predicted tree embeds stale params in the catch-all branch. The server response mismatches, triggering ACTION_SERVER_PATCH with FreshnessPolicy.RefreshAll. During the retry commit, the scrollRef is assigned to the empty catch-all leaf (which renders null and has no client rects), causing its scroll handler to return early without resetting. The actual page leaf runs with ref=null or ref=false, so no segment applies scrollTop=0, leaving the inherited offset.

1. Create app with root layout rendering {children}{modal}. 2. Add app/@modal/default.jsx returning null and app/@modal/[...catchAll]/page.jsx returning null. 3. Add app/page.jsx with a Link to /alice. 4. Add app/[username]/page.jsx with multiple Links to /game/N. 5. Add app/game/[gameId]/page.jsx as a tall dynamic page (force-dynamic optional). 6. Build and start. Navigate to /alice, scroll down, click a game link. The game page opens at the inherited scroll offset instead of top. The issue reproduces in both production and dev, with dev showing alternating failures.

Fixing Code Block

0x7F 45 4C 46 02 01 01 000x90 12 AB 04 C1 7E 33 08
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

Disabling optimisticRouting turns off the new client-side navigation optimizations introduced in 16.3.0, which may slightly increase perceived navigation latency and alter prefetching behavior. This is intended as a temporary workaround until Next.js ships an upstream fix. To roll back, remove the experimental block and restart. If you implement an additional manual scroll-to-top effect, be cautious of double-scrolling or overriding browser scroll restoration; test both dev and production thoroughly.