Fix nested scroll view fling crash by AllinGaming · Pull Request #191130 · flutter/flutter

AllinGaming · 2026-08-14T16:54:06Z

A SliverAppBar whose expandedHeight reacts to scroll direction (a common
"collapse on scroll down" header pattern) can change extent while a fling is
in flight. When that happens, the outer scroll position is transiently
outside [minScrollExtent, maxScrollExtent] for one frame, until the next
layout catches up. _NestedScrollCoordinator._getMetrics assumed the outer
position was always in range when computing ballistic metrics, so this could
either trip an assert (extra >= 0.0 / extra <= 0.0) or, worse, produce a
degenerate minRange == maxRange that gets treated as "no activity needed"
silently abandoning the outer position out of range indefinitely.

This adds _NestedScrollPosition.correctPixelsIfOutOfRange(), called from
the coordinator right before the branch that depends on the outer position
being in range. The "inner list at rest" branch is left untouched: it
already uses the outer's full range (never degenerate) and self-corrects
smoothly via the ballistic simulation, so forcing a correction there isn't
needed and would risk turning a legitimate bounce-back animation into an
abrupt snap.

Fixes #191112

N/A — no changes to the flutter/tests repo.

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Code Review

This pull request introduces a mechanism to correct the outer scroll position of a NestedScrollView when it transiently falls out of range, such as when a header sliver changes size mid-fling. It adds a correctPixelsIfOutOfRange method to _NestedScrollPosition and calls it from the coordinator, along with a regression test. The review feedback suggests using correctPixels instead of forcePixels to silently update the scroll position, which avoids redundant listener notifications and potential framework exceptions during layout or build phases.

AllinGaming · 2026-08-29T18:42:45Z

Anything left to do here?

justinmc · 2026-09-01T22:30:38Z

Sorry I owe you a review, not waiting on you.

justinmc

LGTM 👍 . Makes sense. Thanks for all of the docs/comments on this PR.

justinmc · 2026-09-02T21:49:59Z

    await tester.pumpWidget(buildApp(nested: true));
  });

+  testWidgets('NestedScrollView does not crash when a header sliver shrinks mid-fling', (


I got the same assertion error from #191112 when I ran this test on master 👍

…12760) Manual roll Flutter from 70797e15325e to 5a6cfa7f3d26 (52 revisions) Manual roll requested by [email protected] flutter/flutter@70797e1...5a6cfa7 2026-09-04 [email protected] [tool] Migrate ScreenshotCommand to modular dependency injection (flutter/flutter#190767) 2026-09-04 [email protected] Roll Skia from 8fce167bdded to 93ac1e630d1d (3 revisions) (flutter/flutter#192306) 2026-09-04 [email protected] Add iOS Universal Link integration test (Simulator) (flutter/flutter#191443) 2026-09-04 [email protected] [AGP 9.1.0 Migration #5] Delete getLegacyAndroidExtension and migrate NDK fallback to public DSL (flutter/flutter#192116) 2026-09-04 [email protected] Reland "[tool_tests] Remove bringup from Windows tool_tests_commands_2_2" (#191732) (flutter/flutter#191802) 2026-09-04 [email protected] [flutter_tools] Fix unhandled DebugAdapterException on early process termination (flutter/flutter#192294) 2026-09-04 [email protected] Roll Packages from f9b3954 to 9af9c60 (4 revisions) (flutter/flutter#192292) 2026-09-04 [email protected] Roll Skia from 2e3f7e07eee6 to 8fce167bdded (5 revisions) (flutter/flutter#192283) 2026-09-04 [email protected] Roll Fuchsia Linux SDK from GTZNkoIR_WegRPWgL... to FgDQeF6jb1dVRVh3K... (flutter/flutter#192276) 2026-09-04 [email protected] Roll Skia from b6b00df360e5 to 2e3f7e07eee6 (2 revisions) (flutter/flutter#192275) 2026-09-04 [email protected] [iOS] TextField should support typing accented words with external keyboard (flutter/flutter#191062) 2026-09-04 [email protected] Roll Skia from 1f68c0b16f17 to b6b00df360e5 (7 revisions) (flutter/flutter#192269) 2026-09-04 [email protected] [flutter_tools] add typed enum and defaulted option descriptors (flutter/flutter#191760) 2026-09-04 [email protected] Roll Dart SDK from c2edc382a4f8 to 5501d02b583d (1 revision) (flutter/flutter#192263) 2026-09-04 [email protected] [Linux] Use fences to synchronize frames between OpenGL contexts (flutter/flutter#192098) 2026-09-03 [email protected] Defer semantics geometry updates for blocked branches (flutter/flutter#192146) 2026-09-03 [email protected] Roll Skia from 8d3e197531c6 to 1f68c0b16f17 (8 revisions) (flutter/flutter#192244) 2026-09-03 [email protected] Fix DeleteSurrounding splitting UTF-16 surrogate pairs (flutter/flutter#190514) 2026-09-03 [email protected] Remove no-shuffle from progress indicator test (flutter/flutter#186655) 2026-09-03 [email protected] [material] Remove unused parameters from constructors of generic test class (flutter/flutter#191764) 2026-09-03 [email protected] Handle linear and radial gradients in UberSDF (re-implement after fix) (flutter/flutter#192124) 2026-09-03 [email protected] Roll Dart SDK from fcbfb64f42a1 to c2edc382a4f8 (2 revisions) (flutter/flutter#192240) 2026-09-03 [email protected] Fix parsing of --enable-hcpp-and-surface-control switch and add --no-enable-hcpp tests (flutter/flutter#192202) 2026-09-03 [email protected] Fix issue where shapes rendered with gradient+blur+rotation end up incorrectly cut off (flutter/flutter#192136) 2026-09-03 [email protected] Fix sibling nodes crash under MergeSemantics (flutter/flutter#191587) 2026-09-03 [email protected] Makes backdrop groups operate on the union. (flutter/flutter#191838) 2026-09-03 [email protected] Roll Skia from 008936396810 to 8d3e197531c6 (1 revision) (flutter/flutter#192236) 2026-09-03 [email protected] [docs] Remove superseded AI rules for Flutter (flutter/flutter#192185) 2026-09-03 [email protected] Collect analytics about SwiftPM errors and warnings (flutter/flutter#191746) 2026-09-03 [email protected] Roll Packages from 18fe786 to f9b3954 (7 revisions) (flutter/flutter#192235) 2026-09-03 [email protected] [Linux] Remove frame sharing between OpenGL contexts (flutter/flutter#192150) 2026-09-03 [email protected] Roll Dart SDK from cf79067a1e44 to fcbfb64f42a1 (1 revision) (flutter/flutter#192228) 2026-09-03 [email protected] Roll Skia from 731fe9af4c0b to 008936396810 (3 revisions) (flutter/flutter#192225) 2026-09-03 [email protected] Roll Dart SDK from 700ab60bfe53 to cf79067a1e44 (2 revisions) (flutter/flutter#192219) 2026-09-03 [email protected] Roll Skia from 823f82e18177 to 731fe9af4c0b (5 revisions) (flutter/flutter#192217) 2026-09-03 [email protected] Fixes OverlayPortal semantics bounds corruption (flutter/flutter#192139) 2026-09-03 [email protected] Roll Fuchsia Linux SDK from idslm9FikVLy2K_A-... to GTZNkoIR_WegRPWgL... (flutter/flutter#192215) 2026-09-03 [email protected] Roll Fuchsia Test Scripts from u_fSMsPU22VvUsvSo... to VObjlh3xw2P9sEbC_... (flutter/flutter#192212) 2026-09-03 [email protected] Roll Skia from ae22da2e8308 to 823f82e18177 (13 revisions) (flutter/flutter#192209) 2026-09-02 [email protected] Expose skipTraversal in FocusableActionDetector (flutter/flutter#191308) 2026-09-02 [email protected] Add `IsProgram` mock method to `MockGLESImpl`, use it in `BufferBindingsGLESTest` (flutter/flutter#192196) 2026-09-02 [email protected] Fix nested scroll view fling crash (flutter/flutter#191130) 2026-09-02 [email protected] Fix TabBarView/PageView edge auto-scroll during mouse text selection (flutter/flutter#189544) 2026-09-02 [email protected] Bypass gamma correction when alpha >= 1.0 (flutter/flutter#192193) ...

…lutter#12760) Manual roll Flutter from 70797e15325e to 5a6cfa7f3d26 (52 revisions) Manual roll requested by [email protected] flutter/flutter@70797e1...5a6cfa7 2026-09-04 [email protected] [tool] Migrate ScreenshotCommand to modular dependency injection (flutter/flutter#190767) 2026-09-04 [email protected] Roll Skia from 8fce167bdded to 93ac1e630d1d (3 revisions) (flutter/flutter#192306) 2026-09-04 [email protected] Add iOS Universal Link integration test (Simulator) (flutter/flutter#191443) 2026-09-04 [email protected] [AGP 9.1.0 Migration flutter#5] Delete getLegacyAndroidExtension and migrate NDK fallback to public DSL (flutter/flutter#192116) 2026-09-04 [email protected] Reland "[tool_tests] Remove bringup from Windows tool_tests_commands_2_2" (#191732) (flutter/flutter#191802) 2026-09-04 [email protected] [flutter_tools] Fix unhandled DebugAdapterException on early process termination (flutter/flutter#192294) 2026-09-04 [email protected] Roll Packages from f9b3954 to 9af9c60 (4 revisions) (flutter/flutter#192292) 2026-09-04 [email protected] Roll Skia from 2e3f7e07eee6 to 8fce167bdded (5 revisions) (flutter/flutter#192283) 2026-09-04 [email protected] Roll Fuchsia Linux SDK from GTZNkoIR_WegRPWgL... to FgDQeF6jb1dVRVh3K... (flutter/flutter#192276) 2026-09-04 [email protected] Roll Skia from b6b00df360e5 to 2e3f7e07eee6 (2 revisions) (flutter/flutter#192275) 2026-09-04 [email protected] [iOS] TextField should support typing accented words with external keyboard (flutter/flutter#191062) 2026-09-04 [email protected] Roll Skia from 1f68c0b16f17 to b6b00df360e5 (7 revisions) (flutter/flutter#192269) 2026-09-04 [email protected] [flutter_tools] add typed enum and defaulted option descriptors (flutter/flutter#191760) 2026-09-04 [email protected] Roll Dart SDK from c2edc382a4f8 to 5501d02b583d (1 revision) (flutter/flutter#192263) 2026-09-04 [email protected] [Linux] Use fences to synchronize frames between OpenGL contexts (flutter/flutter#192098) 2026-09-03 [email protected] Defer semantics geometry updates for blocked branches (flutter/flutter#192146) 2026-09-03 [email protected] Roll Skia from 8d3e197531c6 to 1f68c0b16f17 (8 revisions) (flutter/flutter#192244) 2026-09-03 [email protected] Fix DeleteSurrounding splitting UTF-16 surrogate pairs (flutter/flutter#190514) 2026-09-03 [email protected] Remove no-shuffle from progress indicator test (flutter/flutter#186655) 2026-09-03 [email protected] [material] Remove unused parameters from constructors of generic test class (flutter/flutter#191764) 2026-09-03 [email protected] Handle linear and radial gradients in UberSDF (re-implement after fix) (flutter/flutter#192124) 2026-09-03 [email protected] Roll Dart SDK from fcbfb64f42a1 to c2edc382a4f8 (2 revisions) (flutter/flutter#192240) 2026-09-03 [email protected] Fix parsing of --enable-hcpp-and-surface-control switch and add --no-enable-hcpp tests (flutter/flutter#192202) 2026-09-03 [email protected] Fix issue where shapes rendered with gradient+blur+rotation end up incorrectly cut off (flutter/flutter#192136) 2026-09-03 [email protected] Fix sibling nodes crash under MergeSemantics (flutter/flutter#191587) 2026-09-03 [email protected] Makes backdrop groups operate on the union. (flutter/flutter#191838) 2026-09-03 [email protected] Roll Skia from 008936396810 to 8d3e197531c6 (1 revision) (flutter/flutter#192236) 2026-09-03 [email protected] [docs] Remove superseded AI rules for Flutter (flutter/flutter#192185) 2026-09-03 [email protected] Collect analytics about SwiftPM errors and warnings (flutter/flutter#191746) 2026-09-03 [email protected] Roll Packages from 18fe786 to f9b3954 (7 revisions) (flutter/flutter#192235) 2026-09-03 [email protected] [Linux] Remove frame sharing between OpenGL contexts (flutter/flutter#192150) 2026-09-03 [email protected] Roll Dart SDK from cf79067a1e44 to fcbfb64f42a1 (1 revision) (flutter/flutter#192228) 2026-09-03 [email protected] Roll Skia from 731fe9af4c0b to 008936396810 (3 revisions) (flutter/flutter#192225) 2026-09-03 [email protected] Roll Dart SDK from 700ab60bfe53 to cf79067a1e44 (2 revisions) (flutter/flutter#192219) 2026-09-03 [email protected] Roll Skia from 823f82e18177 to 731fe9af4c0b (5 revisions) (flutter/flutter#192217) 2026-09-03 [email protected] Fixes OverlayPortal semantics bounds corruption (flutter/flutter#192139) 2026-09-03 [email protected] Roll Fuchsia Linux SDK from idslm9FikVLy2K_A-... to GTZNkoIR_WegRPWgL... (flutter/flutter#192215) 2026-09-03 [email protected] Roll Fuchsia Test Scripts from u_fSMsPU22VvUsvSo... to VObjlh3xw2P9sEbC_... (flutter/flutter#192212) 2026-09-03 [email protected] Roll Skia from ae22da2e8308 to 823f82e18177 (13 revisions) (flutter/flutter#192209) 2026-09-02 [email protected] Expose skipTraversal in FocusableActionDetector (flutter/flutter#191308) 2026-09-02 [email protected] Add `IsProgram` mock method to `MockGLESImpl`, use it in `BufferBindingsGLESTest` (flutter/flutter#192196) 2026-09-02 [email protected] Fix nested scroll view fling crash (flutter/flutter#191130) 2026-09-02 [email protected] Fix TabBarView/PageView edge auto-scroll during mouse text selection (flutter/flutter#189544) 2026-09-02 [email protected] Bypass gamma correction when alpha >= 1.0 (flutter/flutter#192193) ...

AllinGaming added 3 commits August 14, 2026 18:16

Fix NestedScrollView crash when header sliver extent changes mid-fling

dec15fc

Fix NestedScrollView crash when header sliver extent changes mid-fling

f2ce96c

Fix NestedScrollView crash when header sliver extent changes mid-fling

303eafd

github-actions Bot added framework flutter/packages/flutter repository. See also f: labels. f: scrolling Viewports, list views, slivers, etc. labels Aug 14, 2026

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Comment thread packages/flutter/lib/src/widgets/nested_scroll_view.dart Outdated

Use correctPixels instead of forcePixels to avoid unsafe notifyListeners

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justinmc requested review from justinmc and victorsanni August 18, 2026 22:04

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justinmc added the CICD Run CI/CD label Aug 21, 2026

Merge branch 'master' into fix-nested-scroll-view-fling-crash

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AllinGaming and others added 2 commits August 22, 2026 15:49

Address review: drop Material deps from test, add guard, trim comments

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Merge branch 'master' into fix-nested-scroll-view-fling-crash

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victorsanni self-requested a review August 26, 2026 00:41

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AllinGaming added 2 commits August 28, 2026 15:31

Merge branch 'master' into fix-nested-scroll-view-fling-crash

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Merge branch 'master' into fix-nested-scroll-view-fling-crash

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justinmc added the CICD Run CI/CD label Sep 1, 2026

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Merged via the queue into flutter:master with commit 0968ec9 Sep 3, 2026
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Roll Flutter from 0cbd1a4be0a4 to 8370b2b58b71 (48 revisions) flutter/packages#12738

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Roll Flutter from 0cbd1a4be0a4 to 153a0dea7f93 (49 revisions) flutter/packages#12740

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justinmc mentioned this pull request Sep 4, 2026

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Fix nested scroll view fling crash - #191130

Fix nested scroll view fling crash#191130
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AllinGaming commented Aug 14, 2026

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