Fix Carousel crashes when using PageStorageKey by huycozy · Pull Request #166817 · flutter/flutter

huycozy · 2025-04-09T07:57:41Z

FixCarouselView: using PageStorageKey throws Null check operator used on a null value #166067
PageStorage is usually used to save and restore offset of scrollable widget when the widget is recreated in practice. From the crash stack trace in bug report, it happens when oldViewportDimensions gets a null value. Tracing it down, it’s due to hasViewportDimension is false. There might be a very brief moment when the scroll metrics are being reconstructed, and the viewport dimensions are not yet ready, which triggers the crash. If a PageStorageKey is not specified, the scroll position would be newly created fresh each time, avoiding this restoration process and the associated null state.
The fix is simply to not force casting oldViewportDimensions!, instead, it falls back to viewportDimension which is non-null for safety.

Pre-launch Checklist

I read the Contributor Guide and followed the process outlined there for submitting PRs.
I read the Tree Hygiene wiki page, which explains my responsibilities.
I read and followed the Flutter Style Guide, including Features we expect every widget to implement.
I signed the CLA.
I listed at least one issue that this PR fixes in the description above.
I updated/added relevant documentation (doc comments with ///).
I added new tests to check the change I am making, or this PR is test-exempt.
I followed the breaking change policy and added Data Driven Fixes where supported.
All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel on Discord.

QuncCccccc

LGTM! Thank you for the explanation in the PR description!

flutter/flutter@aef4718...ecabb1a 2025-04-17 15619084+vashworth@users.noreply.github.com Hide error on mDNS registration failure and print warning in flutter attach (flutter/flutter#166782) 2025-04-17 bruno.leroux@gmail.com Add support for language hints in TextFields (Android only) (flutter/flutter#165554) 2025-04-17 engine-flutter-autoroll@skia.org Roll Skia from d8f13372549d to cc2b57434651 (1 revision) (flutter/flutter#167331) 2025-04-17 bruno.leroux@gmail.com Add DropdownMenu.restorationId (flutter/flutter#166684) 2025-04-17 engine-flutter-autoroll@skia.org Roll Skia from 3d6165b70199 to d8f13372549d (14 revisions) (flutter/flutter#167325) 2025-04-17 stanleycocoa@gmail.com fix(CircularProgressIndicator.adaptive): strokeWidth default value (flutter/flutter#165370) 2025-04-17 ahmedelsaayid@gmail.com Remove unnecessary builder (flutter/flutter#166623) 2025-04-17 34871572+gmackall@users.noreply.github.com Add a `gradle_errors.dart`entry for missing NDK source.properties file (flutter/flutter#167320) 2025-04-17 engine-flutter-autoroll@skia.org Roll Skia from 6627deb65939 to 3d6165b70199 (1 revision) (flutter/flutter#167255) 2025-04-17 engine-flutter-autoroll@skia.org Manual roll Dart SDK from 87965ab4864e to 992221a362ec (35 revisions) (flutter/flutter#167243) 2025-04-16 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from 7bWzHwIPBTyU6R9nO... to m8Aln7fTF_8zy1V9N... (flutter/flutter#167312) 2025-04-16 15619084+vashworth@users.noreply.github.com Don't throw on error for mDNS when searching for Dart VML url on core devices (flutter/flutter#167135) 2025-04-16 34465683+rkishan516@users.noreply.github.com Fix: Localization for non zero time in 24 hours format (flutter/flutter#164885) 2025-04-16 30870216+gaaclarke@users.noreply.github.com Updated docstrings for TextureContents (flutter/flutter#167221) 2025-04-16 30870216+gaaclarke@users.noreply.github.com Broke cyclical dependency with dlpath and typographer. (flutter/flutter#167293) 2025-04-16 34871572+gmackall@users.noreply.github.com Set an additional CMake arg in `forceNdkDownload` to make the task name align with the `BuildType` (flutter/flutter#167240) 2025-04-16 huy@nevercode.io Fix Carousel crashes when using PageStorageKey (flutter/flutter#166817) 2025-04-16 jason-simmons@users.noreply.github.com Revert "Removed superfluous copy in license checker (#167146)" (flutter/flutter#167246) 2025-04-16 dacoharkes@google.com [native assets] Roll dependencies (flutter/flutter#167287) 2025-04-16 fluttergithubbot@gmail.com Marks Linux_pixel_7pro static_path_stroke_tessellation_perf__timeline_summary to be unflaky (flutter/flutter#167259) 2025-04-16 34465683+rkishan516@users.noreply.github.com Feat: Add carousel view theme (flutter/flutter#164769) 2025-04-16 fluttergithubbot@gmail.com Marks Mac_ios dynamic_path_stroke_tessellation_perf_ios__timeline_summary to be unflaky (flutter/flutter#167261) 2025-04-16 jason-simmons@users.noreply.github.com When using --local-web-sdk, use a locally built Dart SDK if one is available (flutter/flutter#166732) 2025-04-16 30870216+gaaclarke@users.noreply.github.com Added emulator version to doctor (flutter/flutter#167236) 2025-04-16 fluttergithubbot@gmail.com Marks Mac_ios static_path_stroke_tessellation_perf_ios__timeline_summary to be unflaky (flutter/flutter#167260) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC stuartmorgan@google.com,tarrinneal@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

- Fixflutter#166067 - PageStorage is usually used to save and restore offset of scrollable widget when the widget is recreated in practice. From the crash stack trace in bug report, it happens when [oldViewportDimensions gets a null value](https://github.com/flutter/flutter/blob/3fa9b387052363e413b906da08c1b1d2d4140dfb/packages/flutter/lib/src/material/carousel.dart#L1472-L1485). Tracing it down, it’s due to [hasViewportDimension is false](https://github.com/flutter/flutter/blob/3fa9b387052363e413b906da08c1b1d2d4140dfb/packages/flutter/lib/src/widgets/scroll_position.dart#L275). There might be a very brief moment when the scroll metrics are being reconstructed, and the viewport dimensions are not yet ready, which triggers the crash. If a PageStorageKey is not specified, the scroll position would be newly created fresh each time, avoiding this restoration process and the associated null state. - The fix is simply to not force casting `oldViewportDimensions!`, instead, it falls back to `viewportDimension` which is non-null for safety. ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [x] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement]. - [x] I signed the [CLA]. - [x] I listed at least one issue that this PR fixes in the description above. - [x] I updated/added relevant documentation (doc comments with `///`). - [x] I added new tests to check the change I am making, or this PR is [test-exempt]. - [x] I followed the [breaking change policy] and added [Data Driven Fixes] where supported. - [x] All existing and new tests are passing. If you need help, consider asking for advice on the #hackers-new channel on [Discord].  [Contributor Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview [Tree Hygiene]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md [test-exempt]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests [Flutter Style Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md [Features we expect every widget to implement]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement [CLA]: https://cla.developers.google.com/ [flutter/tests]: https://github.com/flutter/tests [breaking change policy]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes [Discord]: https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md [Data Driven Fixes]: https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md

flutter/flutter@aef4718...ecabb1a 2025-04-17 15619084+vashworth@users.noreply.github.com Hide error on mDNS registration failure and print warning in flutter attach (flutter/flutter#166782) 2025-04-17 bruno.leroux@gmail.com Add support for language hints in TextFields (Android only) (flutter/flutter#165554) 2025-04-17 engine-flutter-autoroll@skia.org Roll Skia from d8f13372549d to cc2b57434651 (1 revision) (flutter/flutter#167331) 2025-04-17 bruno.leroux@gmail.com Add DropdownMenu.restorationId (flutter/flutter#166684) 2025-04-17 engine-flutter-autoroll@skia.org Roll Skia from 3d6165b70199 to d8f13372549d (14 revisions) (flutter/flutter#167325) 2025-04-17 stanleycocoa@gmail.com fix(CircularProgressIndicator.adaptive): strokeWidth default value (flutter/flutter#165370) 2025-04-17 ahmedelsaayid@gmail.com Remove unnecessary builder (flutter/flutter#166623) 2025-04-17 34871572+gmackall@users.noreply.github.com Add a `gradle_errors.dart`entry for missing NDK source.properties file (flutter/flutter#167320) 2025-04-17 engine-flutter-autoroll@skia.org Roll Skia from 6627deb65939 to 3d6165b70199 (1 revision) (flutter/flutter#167255) 2025-04-17 engine-flutter-autoroll@skia.org Manual roll Dart SDK from 87965ab4864e to 992221a362ec (35 revisions) (flutter/flutter#167243) 2025-04-16 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from 7bWzHwIPBTyU6R9nO... to m8Aln7fTF_8zy1V9N... (flutter/flutter#167312) 2025-04-16 15619084+vashworth@users.noreply.github.com Don't throw on error for mDNS when searching for Dart VML url on core devices (flutter/flutter#167135) 2025-04-16 34465683+rkishan516@users.noreply.github.com Fix: Localization for non zero time in 24 hours format (flutter/flutter#164885) 2025-04-16 30870216+gaaclarke@users.noreply.github.com Updated docstrings for TextureContents (flutter/flutter#167221) 2025-04-16 30870216+gaaclarke@users.noreply.github.com Broke cyclical dependency with dlpath and typographer. (flutter/flutter#167293) 2025-04-16 34871572+gmackall@users.noreply.github.com Set an additional CMake arg in `forceNdkDownload` to make the task name align with the `BuildType` (flutter/flutter#167240) 2025-04-16 huy@nevercode.io Fix Carousel crashes when using PageStorageKey (flutter/flutter#166817) 2025-04-16 jason-simmons@users.noreply.github.com Revert "Removed superfluous copy in license checker (#167146)" (flutter/flutter#167246) 2025-04-16 dacoharkes@google.com [native assets] Roll dependencies (flutter/flutter#167287) 2025-04-16 fluttergithubbot@gmail.com Marks Linux_pixel_7pro static_path_stroke_tessellation_perf__timeline_summary to be unflaky (flutter/flutter#167259) 2025-04-16 34465683+rkishan516@users.noreply.github.com Feat: Add carousel view theme (flutter/flutter#164769) 2025-04-16 fluttergithubbot@gmail.com Marks Mac_ios dynamic_path_stroke_tessellation_perf_ios__timeline_summary to be unflaky (flutter/flutter#167261) 2025-04-16 jason-simmons@users.noreply.github.com When using --local-web-sdk, use a locally built Dart SDK if one is available (flutter/flutter#166732) 2025-04-16 30870216+gaaclarke@users.noreply.github.com Added emulator version to doctor (flutter/flutter#167236) 2025-04-16 fluttergithubbot@gmail.com Marks Mac_ios static_path_stroke_tessellation_perf_ios__timeline_summary to be unflaky (flutter/flutter#167260) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC stuartmorgan@google.com,tarrinneal@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

martin-ideeri · 2025-07-24T08:51:38Z

Has this been released ? I'm still experiencing this issue in flutter 3.32.7

huycozy · 2025-07-24T09:32:35Z

Has this been released ? I'm still experiencing this issue in flutter 3.32.7

This hasn't landed in 3.32.7 yet, see 2c516f2.

…er#166817)

- Fixflutter#166067 - PageStorage is usually used to save and restore offset of scrollable widget when the widget is recreated in practice. From the crash stack trace in bug report, it happens when [oldViewportDimensions gets a null value](https://github.com/flutter/flutter/blob/3fa9b387052363e413b906da08c1b1d2d4140dfb/packages/flutter/lib/src/material/carousel.dart#L1472-L1485). Tracing it down, it’s due to [hasViewportDimension is false](https://github.com/flutter/flutter/blob/3fa9b387052363e413b906da08c1b1d2d4140dfb/packages/flutter/lib/src/widgets/scroll_position.dart#L275). There might be a very brief moment when the scroll metrics are being reconstructed, and the viewport dimensions are not yet ready, which triggers the crash. If a PageStorageKey is not specified, the scroll position would be newly created fresh each time, avoiding this restoration process and the associated null state. - The fix is simply to not force casting `oldViewportDimensions!`, instead, it falls back to `viewportDimension` which is non-null for safety. ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [x] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement]. - [x] I signed the [CLA]. - [x] I listed at least one issue that this PR fixes in the description above. - [x] I updated/added relevant documentation (doc comments with `///`). - [x] I added new tests to check the change I am making, or this PR is [test-exempt]. - [x] I followed the [breaking change policy] and added [Data Driven Fixes] where supported. - [x] All existing and new tests are passing. If you need help, consider asking for advice on the #hackers-new channel on [Discord].  [Contributor Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview [Tree Hygiene]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md [test-exempt]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests [Flutter Style Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md [Features we expect every widget to implement]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement [CLA]: https://cla.developers.google.com/ [flutter/tests]: https://github.com/flutter/tests [breaking change policy]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes [Discord]: https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md [Data Driven Fixes]: https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md

…er#166817)

flutter/flutter@aef4718...ecabb1a 2025-04-17 15619084+vashworth@users.noreply.github.com Hide error on mDNS registration failure and print warning in flutter attach (flutter/flutter#166782) 2025-04-17 bruno.leroux@gmail.com Add support for language hints in TextFields (Android only) (flutter/flutter#165554) 2025-04-17 engine-flutter-autoroll@skia.org Roll Skia from d8f13372549d to cc2b57434651 (1 revision) (flutter/flutter#167331) 2025-04-17 bruno.leroux@gmail.com Add DropdownMenu.restorationId (flutter/flutter#166684) 2025-04-17 engine-flutter-autoroll@skia.org Roll Skia from 3d6165b70199 to d8f13372549d (14 revisions) (flutter/flutter#167325) 2025-04-17 stanleycocoa@gmail.com fix(CircularProgressIndicator.adaptive): strokeWidth default value (flutter/flutter#165370) 2025-04-17 ahmedelsaayid@gmail.com Remove unnecessary builder (flutter/flutter#166623) 2025-04-17 34871572+gmackall@users.noreply.github.com Add a `gradle_errors.dart`entry for missing NDK source.properties file (flutter/flutter#167320) 2025-04-17 engine-flutter-autoroll@skia.org Roll Skia from 6627deb65939 to 3d6165b70199 (1 revision) (flutter/flutter#167255) 2025-04-17 engine-flutter-autoroll@skia.org Manual roll Dart SDK from 87965ab4864e to 992221a362ec (35 revisions) (flutter/flutter#167243) 2025-04-16 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from 7bWzHwIPBTyU6R9nO... to m8Aln7fTF_8zy1V9N... (flutter/flutter#167312) 2025-04-16 15619084+vashworth@users.noreply.github.com Don't throw on error for mDNS when searching for Dart VML url on core devices (flutter/flutter#167135) 2025-04-16 34465683+rkishan516@users.noreply.github.com Fix: Localization for non zero time in 24 hours format (flutter/flutter#164885) 2025-04-16 30870216+gaaclarke@users.noreply.github.com Updated docstrings for TextureContents (flutter/flutter#167221) 2025-04-16 30870216+gaaclarke@users.noreply.github.com Broke cyclical dependency with dlpath and typographer. (flutter/flutter#167293) 2025-04-16 34871572+gmackall@users.noreply.github.com Set an additional CMake arg in `forceNdkDownload` to make the task name align with the `BuildType` (flutter/flutter#167240) 2025-04-16 huy@nevercode.io Fix Carousel crashes when using PageStorageKey (flutter/flutter#166817) 2025-04-16 jason-simmons@users.noreply.github.com Revert "Removed superfluous copy in license checker (#167146)" (flutter/flutter#167246) 2025-04-16 dacoharkes@google.com [native assets] Roll dependencies (flutter/flutter#167287) 2025-04-16 fluttergithubbot@gmail.com Marks Linux_pixel_7pro static_path_stroke_tessellation_perf__timeline_summary to be unflaky (flutter/flutter#167259) 2025-04-16 34465683+rkishan516@users.noreply.github.com Feat: Add carousel view theme (flutter/flutter#164769) 2025-04-16 fluttergithubbot@gmail.com Marks Mac_ios dynamic_path_stroke_tessellation_perf_ios__timeline_summary to be unflaky (flutter/flutter#167261) 2025-04-16 jason-simmons@users.noreply.github.com When using --local-web-sdk, use a locally built Dart SDK if one is available (flutter/flutter#166732) 2025-04-16 30870216+gaaclarke@users.noreply.github.com Added emulator version to doctor (flutter/flutter#167236) 2025-04-16 fluttergithubbot@gmail.com Marks Mac_ios static_path_stroke_tessellation_perf_ios__timeline_summary to be unflaky (flutter/flutter#167260) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC stuartmorgan@google.com,tarrinneal@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

huycozy self-assigned this Apr 9, 2025

github-actionsBot added framework flutter/packages/flutter repository. See also f: labels. p: material_ui material_ui package in flutter/packages labels Apr 9, 2025

Fix Carousel crashes when using PageStorageKey
6bbeff3

huycozy force-pushed the fix-carouselview-key-null-exception-166067 branch from a1970ce to 6bbeff3Compare April 9, 2025 09:51

huycozy requested a review from QuncCccccc April 9, 2025 11:32

QuncCccccc approved these changes Apr 16, 2025
View reviewed changes

QuncCccccc added the autosubmit Merge PR when tree becomes green via auto submit App label Apr 16, 2025

auto-submitBot added this pull request to the merge queue Apr 16, 2025

Merged via the queue into flutter:master with commit 2c516f2Apr 16, 2025

flutter-dashboardBot removed the autosubmit Merge PR when tree becomes green via auto submit App label Apr 16, 2025

huycozy deleted the fix-carouselview-key-null-exception-166067 branch April 17, 2025 02:44

engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Apr 17, 2025
2c516f2Fix Carousel crashes when using PageStorageKey (flutter/flutt…
4588b0d
…er#166817)

engine-flutter-autoroll mentioned this pull request Apr 17, 2025
Roll Flutter from aef4718b3956 to ecabb1a05212 (25 revisions) flutter/packages#9104
Merged

engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Aug 14, 2025
2c516f2Fix Carousel crashes when using PageStorageKey (flutter/flutt…
1fe488a
…er#166817)

engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Aug 14, 2025
2c516f2Fix Carousel crashes when using PageStorageKey (flutter/flutt…
ae582ee
…er#166817)

engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Aug 15, 2025
2c516f2Fix Carousel crashes when using PageStorageKey (flutter/flutt…
fb13636
…er#166817)

engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Aug 15, 2025
2c516f2Fix Carousel crashes when using PageStorageKey (flutter/flutt…
050ec5e
…er#166817)

engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Aug 16, 2025
2c516f2Fix Carousel crashes when using PageStorageKey (flutter/flutt…
21baeb9
…er#166817)

Navigation Menu

Uh oh!

Fix Carousel crashes when using PageStorageKey - #166817

Fix Carousel crashes when using PageStorageKey#166817
auto-submit[bot] merged 1 commit into
flutter:masterfrom
huycozy:fix-carouselview-key-null-exception-166067

huycozy commented Apr 9, 2025

Uh oh!

QuncCccccc left a comment

Uh oh!

martin-ideeri commented Jul 24, 2025

Uh oh!

huycozy commented Jul 24, 2025

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Uh oh!

Conversation

huycozy commented Apr 9, 2025

Pre-launch Checklist

Uh oh!

QuncCccccc left a comment

Choose a reason for hiding this comment

Uh oh!

martin-ideeri commented Jul 24, 2025

Uh oh!

huycozy commented Jul 24, 2025

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants