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Update TickerMode.getValuesNotifier to handle initialization during State.dispose#185248

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Update TickerMode.getValuesNotifier to handle initialization during State.dispose#185248
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@nate-thegrate

@nate-thegrate nate-thegrate commented Apr 18, 2026 •
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Currently, TickerMode.getValuesNotifier assumes that getInheritedWidgetOfExactType is safe to call, but there's an edge case where a widget defines an animation controller field and then is disposed of before that field is referenced elsewhere.

This PR updates the logic in getValuesNotifier() to handle that situation instead of throwing an error.

related to #153644

@github-actions github-actions Bot added the framework flutter/packages/flutter repository. See also f: labels. label Apr 18, 2026
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Code Review

This pull request updates TickerMode.getValuesNotifier to return a fallback value when the context is unmounted, preventing assertion errors that occur when late final animation controllers are disposed. It also adds regression tests for SingleTickerProviderStateMixin and TickerProviderStateMixin. The review feedback suggests removing the kDebugMode check to simplify the logic and ensure consistent behavior across all build modes.

Comment thread packages/flutter/lib/src/widgets/ticker_provider.dart Outdated
// The getInheritedWidgetOfExactType() method throws an assertion error if called during
// State.dispose(), which becomes a problem when an animation controller is set as a
// late final class member and isn't referenced until then.
if (kDebugMode && !context.mounted) {

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medium

The kDebugMode check is not strictly necessary here. If context.mounted is false, the element is defunct and getInheritedWidgetOfExactType would return null in release mode anyway (after a more expensive lookup). Removing kDebugMode simplifies the logic and provides a consistent, slightly more efficient path in all modes when the context is unmounted. This also aligns with the general practice of using context.mounted to guard against using a defunct context.

    if (!context.mounted) {
References
  1. Optimize for readability and avoid unnecessary complexity. (link)

@nate-thegrate nate-thegrate Apr 18, 2026

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SGTM :)

navaronbracke
navaronbracke reviewed Apr 20, 2026
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Comment thread packages/flutter/lib/src/widgets/ticker_provider.dart
const fallback = _ConstantTickerModeDataListenable(TickerModeData.fallback);

// The getInheritedWidgetOfExactType() method throws an assertion error if called during
// State.dispose(), which becomes a problem when an animation controller is set as a

@navaronbracke navaronbracke Apr 20, 2026 •
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This is technically not tied to animation controller, but the consumer of the VSync? (the class that mixes in the ticker provider)

@nate-thegrate nate-thegrate Apr 21, 2026

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When getValuesNotifier is called during State.dispose, I guess you could say the call is tied to both the animation controller and the State subclass that mixes in the ticker provider.

When the animation controller object is being referenced for the first time, the AnimationController constructor is called, which then calls the ticker provider's createTicker method, and inside that method is where TickerMode.getValuesNotifier is eventually called.

Please let me know if I misunderstood your question!

victorsanni
victorsanni approved these changes Apr 24, 2026
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I would normally think we should throw the error anyways. But the fact that getValuesNotifier already has a fallback mechanism makes me think this PR is 👍

Comment thread packages/flutter/lib/src/widgets/ticker_provider.dart
// The getInheritedWidgetOfExactType() method throws an assertion error if called during
// State.dispose(), which becomes a problem when an animation controller is set as a
// late final class member and isn't referenced until then.
if (!context.mounted) {

@victorsanni victorsanni Apr 24, 2026

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context.getInheritedWidgetOfExactType throws if the current lifecycle state is not _ElementLifecycle.active. Is this == context.mounted?

@nate-thegrate nate-thegrate Apr 25, 2026

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That's a good question!

If we land this change, hypothetically TickerMode.getValuesNotifier could still throw an error if a late animation controller is referenced for the first time while an element is in the middle of GlobalKey re-parenting.

But realistically, I don't think this a cause for concern.

@victorsanni victorsanni added the CICD Run CI/CD label Apr 24, 2026
justinmc
justinmc approved these changes Apr 27, 2026
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LGTM 👍 . Is this the only thing blocking #153644? I think I missed that issue when you first created it, but reading through it now, I'm cautiously excited about it. It really simplifies things in the examples you gave at least.

@nate-thegrate

nate-thegrate commented Apr 28, 2026

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Is this the only thing blocking #153644?

I think so! I believe we can do a really nice cleanup once this PR lands.
The point made in #153644 (comment) still stands though; we'd need to consider potential side effects of late initialization, for example:

late final controller = AnimationController(vsync: this)..forward();

The forward() call would probably need to be moved to initState to ensure that it's actually called when we expect it to be.

@justinmc justinmc added the autosubmit Merge PR when tree becomes green via auto submit App label Apr 29, 2026
@auto-submit auto-submit Bot added this pull request to the merge queue Apr 29, 2026
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Roll Flutter from 81bc3d69535f to 707dbc0420a3 (85 revisions)

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2026-05-01 Rusino@users.noreply.github.com Removing TODOs from the WebParagraph code and addressing technical debts. (flutter/flutter#185168)
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2026-05-01 nshahan@google.com [flutter_tools] Bump dwds dependency to v27.1.1 (flutter/flutter#185357)
2026-05-01 engine-flutter-autoroll@skia.org Roll Dart SDK from 6d4a319cbdac to 9aa7097f2e3e (3 revisions) (flutter/flutter#185888)
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2026-05-01 engine-flutter-autoroll@skia.org Roll Skia from 54cc00adde38 to fa1dcb289709 (3 revisions) (flutter/flutter#185880)
2026-05-01 chris@bracken.jp [iOS] Migrate to FlutterFMLTaskRunner(s) (flutter/flutter#185815)
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2026-05-01 engine-flutter-autoroll@skia.org Roll Skia from 2e279266f06a to 54cc00adde38 (3 revisions) (flutter/flutter#185872)
2026-05-01 srawlins@google.com dev: Remove unused parameters (flutter/flutter#185345)
2026-05-01 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from HN5VYzftnf_B8T-n9... to VnzuUefDQR0UhQ1L1... (flutter/flutter#185870)
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2026-05-01 engine-flutter-autoroll@skia.org Roll Dart SDK from d30df3428f2e to 6d4a319cbdac (2 revisions) (flutter/flutter#185862)
2026-05-01 73785960+xfce0@users.noreply.github.com Remove trivial test utility cross-imports from material and cupertino… (flutter/flutter#184295)
2026-05-01 129008657+DaveT1991@users.noreply.github.com Inline test callback painter in tab scaffold test (flutter/flutter#184851)
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2026-04-30 73091075+MohamedRisaldarTA@users.noreply.github.com Added name to AUTHORS (flutter/flutter#185586)
2026-04-30 sanaullah.383@hotmail.com Remove semantics_tester import from raw_material_button_test.dart (flutter/flutter#184806)
2026-04-30 sanaullah.383@hotmail.com Remove semantics_tester import from user_accounts_drawer_header_test.dart (flutter/flutter#184809)
2026-04-30 engine-flutter-autoroll@skia.org Roll Skia from 7b88c5c281e5 to 2e279266f06a (5 revisions) (flutter/flutter#185854)
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2026-04-30 154381524+flutteractionsbot@users.noreply.github.com Sync CHANGELOG.md from stable (flutter/flutter#185838)
2026-04-30 engine-flutter-autoroll@skia.org Roll Dart SDK from 25910e31a6d2 to d30df3428f2e (5 revisions) (flutter/flutter#185839)
2026-04-30 brackenavaron@gmail.com Check cross imports test subfolders (flutter/flutter#185493)
2026-04-30 112751483+shivanshu877@users.noreply.github.com test: inline TestCallbackPainter in cupertino/picker_test.dart (flutter/flutter#185398)
2026-04-30 97480502+b-luk@users.noreply.github.com Update customer testing version (flutter/flutter#185830)
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2026-04-30 engine-flutter-autoroll@skia.org Roll Skia from 26a59aa71eff to 7b88c5c281e5 (1 revision) (flutter/flutter#185821)
2026-04-30 engine-flutter-autoroll@skia.org Roll Skia from 6b4167b4e204 to 26a59aa71eff (4 revisions) (flutter/flutter#185808)
2026-04-30 jhy03261997@gmail.com [a11y] Mark SemanticsNode dirty when customSemanticsActions change  (flutter/flutter#185707)
2026-04-30 engine-flutter-autoroll@skia.org Roll Skia from 1bd2f1cc2746 to 6b4167b4e204 (8 revisions) (flutter/flutter#185799)
2026-04-30 chris@bracken.jp [iOS] Extract FlutterVSyncClient from vsync_waiter_ios (flutter/flutter#185737)
2026-04-30 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from nnv8-SSam6yE8dw4z... to HN5VYzftnf_B8T-n9... (flutter/flutter#185782)
2026-04-29 chris@bracken.jp [iOS] Soften TaskRunner.postTask(delay:task:) delay check (flutter/flutter#185729)
2026-04-29 koji.wakamiya@gmail.com Add reportErrors to ImageStreamListener (flutter/flutter#180327)
2026-04-29 engine-flutter-autoroll@skia.org Roll Skia from f5c781c083c7 to 1bd2f1cc2746 (5 revisions) (flutter/flutter#185761)
2026-04-29 47866232+chunhtai@users.noreply.github.com Update merge semantics logic to merge sibling nodes (flutter/flutter#183745)
2026-04-29 engine-flutter-autoroll@skia.org Roll Packages from ba80f8f to cde5b36 (12 revisions) (flutter/flutter#185748)
2026-04-29 srawlins@google.com examples: Remove unused parameters (flutter/flutter#185346)
2026-04-29 nate.w5687@gmail.com Update TickerMode.getValuesNotifier to handle initialization during State.dispose (flutter/flutter#185248)
2026-04-29 katelovett@google.com Update triage links (flutter/flutter#185714)
2026-04-29 42399845+xxxOVALxxx@users.noreply.github.com Add support for high contrast and color inversion on Android (flutter/flutter#182263)
2026-04-29 engine-flutter-autoroll@skia.org Roll Skia from 05251260fda6 to f5c781c083c7 (2 revisions) (flutter/flutter#185743)
...
creatorpiyush pushed a commit to creatorpiyush/packages that referenced this pull request Jun 10, 2026
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Roll Flutter from 81bc3d69535f to 707dbc0420a3 (85 revisions) (flutte…
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Roll Flutter from 81bc3d69535f to 707dbc0420a3 (85 revisions)

flutter/flutter@81bc3d6...707dbc0

2026-05-01 Rusino@users.noreply.github.com Removing TODOs from the WebParagraph code and addressing technical debts. (flutter/flutter#185168)
2026-05-01 mbrase@google.com Ensure that vulkan_interface.h gets included before vk_mem_alloc.h (flutter/flutter#185777)
2026-05-01 nshahan@google.com [flutter_tools] Bump dwds dependency to v27.1.1 (flutter/flutter#185357)
2026-05-01 engine-flutter-autoroll@skia.org Roll Dart SDK from 6d4a319cbdac to 9aa7097f2e3e (3 revisions) (flutter/flutter#185888)
2026-05-01 engine-flutter-autoroll@skia.org Roll Skia from fa1dcb289709 to 7ac6d42f2fd0 (1 revision) (flutter/flutter#185887)
2026-05-01 engine-flutter-autoroll@skia.org Roll Skia from 54cc00adde38 to fa1dcb289709 (3 revisions) (flutter/flutter#185880)
2026-05-01 chris@bracken.jp [iOS] Migrate to FlutterFMLTaskRunner(s) (flutter/flutter#185815)
2026-05-01 ad13dtu@gmail.com Remove material imports from navigator_on_did_remove_page_test and scrollable_in_overlay_test (flutter/flutter#182546)
2026-05-01 engine-flutter-autoroll@skia.org Roll Skia from 2e279266f06a to 54cc00adde38 (3 revisions) (flutter/flutter#185872)
2026-05-01 srawlins@google.com dev: Remove unused parameters (flutter/flutter#185345)
2026-05-01 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from HN5VYzftnf_B8T-n9... to VnzuUefDQR0UhQ1L1... (flutter/flutter#185870)
2026-05-01 robert.ancell@canonical.com Use g_free when using glib memory allocation (flutter/flutter#185519)
2026-05-01 engine-flutter-autoroll@skia.org Roll Dart SDK from d30df3428f2e to 6d4a319cbdac (2 revisions) (flutter/flutter#185862)
2026-05-01 73785960+xfce0@users.noreply.github.com Remove trivial test utility cross-imports from material and cupertino… (flutter/flutter#184295)
2026-05-01 129008657+DaveT1991@users.noreply.github.com Inline test callback painter in tab scaffold test (flutter/flutter#184851)
2026-05-01 jhy03261997@gmail.com [a11y] Add support for high contrast themes in the a11y assessments app  (flutter/flutter#185801)
2026-05-01 jhy03261997@gmail.com [a11y assessment app] Use default color for banner (flutter/flutter#185804)
2026-04-30 73091075+MohamedRisaldarTA@users.noreply.github.com Added name to AUTHORS (flutter/flutter#185586)
2026-04-30 sanaullah.383@hotmail.com Remove semantics_tester import from raw_material_button_test.dart (flutter/flutter#184806)
2026-04-30 sanaullah.383@hotmail.com Remove semantics_tester import from user_accounts_drawer_header_test.dart (flutter/flutter#184809)
2026-04-30 engine-flutter-autoroll@skia.org Roll Skia from 7b88c5c281e5 to 2e279266f06a (5 revisions) (flutter/flutter#185854)
2026-04-30 evanwall@buffalo.edu Handle symmetric rectangular and elliptical round super ellipses in the uber SDF renderer  (flutter/flutter#185695)
2026-04-30 15619084+vashworth@users.noreply.github.com Match on process name before killing for SwiftPM (flutter/flutter#185774)
2026-04-30 154381524+flutteractionsbot@users.noreply.github.com Sync CHANGELOG.md from stable (flutter/flutter#185838)
2026-04-30 engine-flutter-autoroll@skia.org Roll Dart SDK from 25910e31a6d2 to d30df3428f2e (5 revisions) (flutter/flutter#185839)
2026-04-30 brackenavaron@gmail.com Check cross imports test subfolders (flutter/flutter#185493)
2026-04-30 112751483+shivanshu877@users.noreply.github.com test: inline TestCallbackPainter in cupertino/picker_test.dart (flutter/flutter#185398)
2026-04-30 97480502+b-luk@users.noreply.github.com Update customer testing version (flutter/flutter#185830)
2026-04-30 jason-simmons@users.noreply.github.com Adapt the Metal shader library output list for debug versus release mode (flutter/flutter#185798)
2026-04-30 jason-simmons@users.noreply.github.com [Impeller] Port a recent Vulkan swapchain fence waiting fix to the AHB version of the swapchain (flutter/flutter#185763)
2026-04-30 engine-flutter-autoroll@skia.org Roll Skia from 26a59aa71eff to 7b88c5c281e5 (1 revision) (flutter/flutter#185821)
2026-04-30 engine-flutter-autoroll@skia.org Roll Skia from 6b4167b4e204 to 26a59aa71eff (4 revisions) (flutter/flutter#185808)
2026-04-30 jhy03261997@gmail.com [a11y] Mark SemanticsNode dirty when customSemanticsActions change  (flutter/flutter#185707)
2026-04-30 engine-flutter-autoroll@skia.org Roll Skia from 1bd2f1cc2746 to 6b4167b4e204 (8 revisions) (flutter/flutter#185799)
2026-04-30 chris@bracken.jp [iOS] Extract FlutterVSyncClient from vsync_waiter_ios (flutter/flutter#185737)
2026-04-30 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from nnv8-SSam6yE8dw4z... to HN5VYzftnf_B8T-n9... (flutter/flutter#185782)
2026-04-29 chris@bracken.jp [iOS] Soften TaskRunner.postTask(delay:task:) delay check (flutter/flutter#185729)
2026-04-29 koji.wakamiya@gmail.com Add reportErrors to ImageStreamListener (flutter/flutter#180327)
2026-04-29 engine-flutter-autoroll@skia.org Roll Skia from f5c781c083c7 to 1bd2f1cc2746 (5 revisions) (flutter/flutter#185761)
2026-04-29 47866232+chunhtai@users.noreply.github.com Update merge semantics logic to merge sibling nodes (flutter/flutter#183745)
2026-04-29 engine-flutter-autoroll@skia.org Roll Packages from ba80f8f to cde5b36 (12 revisions) (flutter/flutter#185748)
2026-04-29 srawlins@google.com examples: Remove unused parameters (flutter/flutter#185346)
2026-04-29 nate.w5687@gmail.com Update TickerMode.getValuesNotifier to handle initialization during State.dispose (flutter/flutter#185248)
2026-04-29 katelovett@google.com Update triage links (flutter/flutter#185714)
2026-04-29 42399845+xxxOVALxxx@users.noreply.github.com Add support for high contrast and color inversion on Android (flutter/flutter#182263)
2026-04-29 engine-flutter-autoroll@skia.org Roll Skia from 05251260fda6 to f5c781c083c7 (2 revisions) (flutter/flutter#185743)
...
@nate-thegrate nate-thegrate deleted the late-animation branch June 12, 2026 21:47
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