Unreal Engine Issues and Bug Tracker (UE-21493)

Description

If the user uses "Get child at" with an invalid index and then hooks up the return value to a "Scroll Widget into View" node's "Widget to Find" pin it will cause a crash

Steps to Reproduce

Open the Editor
Create a new widget blueprint
Add a scroll box widget (don't add children)
Open the event graph and create the blueprint in the attached image
Save and compile
Open level blueprint
Add the widget blueprint to the viewport on begin play
Play in editor
Notice the editor crashes

Callstack

MachineId:E74C21034048BDD873CC6C9A3913CF6C
EpicAccountId:ccbf39de6f9245c0aa23f8e57cc8a566

Access violation - code c0000005 (first/second chance not available)

""

UE4Editor_UMG!UWidget::GetCachedWidget() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\umg\private\components\widget.cpp:555]
UE4Editor_UMG!UScrollBox::ScrollWidgetIntoView() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\umg\private\components\scrollbox.cpp:133]
UE4Editor_UMG!UScrollBox::execScrollWidgetIntoView() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\umg\public\components\scrollbox.h:13]
UE4Editor_CoreUObject!UFunction::Invoke() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\coreuobject\private\uobject\class.cpp:4195]
UE4Editor_CoreUObject!UObject::CallFunction() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\coreuobject\private\uobject\scriptcore.cpp:484]
UE4Editor_CoreUObject!UObject::ProcessContextOpcode() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\coreuobject\private\uobject\scriptcore.cpp:1755]
UE4Editor_CoreUObject!UObject::ProcessInternal() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\coreuobject\private\uobject\scriptcore.cpp:698]
UE4Editor_CoreUObject!UFunction::Invoke() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\coreuobject\private\uobject\class.cpp:4195]
UE4Editor_CoreUObject!UObject::ProcessEvent() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\coreuobject\private\uobject\scriptcore.cpp:1050]
UE4Editor_UMG!UUserWidget::OnWidgetRebuilt() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\umg\private\userwidget.cpp:330]
UE4Editor_UMG!UWidget::TakeWidget() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\umg\private\components\widget.cpp:522]
UE4Editor_UMG!UUserWidget::MakeViewportWidget() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\umg\private\userwidget.cpp:423]
UE4Editor_UMG!UUserWidget::AddToScreen() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\umg\private\userwidget.cpp:468]
UE4Editor_UMG!UUserWidget::execAddToViewport() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\umg\public\blueprint\userwidget.h:143]
UE4Editor_CoreUObject!UFunction::Invoke() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\coreuobject\private\uobject\class.cpp:4195]
UE4Editor_CoreUObject!UObject::CallFunction() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\coreuobject\private\uobject\scriptcore.cpp:484]
UE4Editor_CoreUObject!UObject::ProcessContextOpcode() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\coreuobject\private\uobject\scriptcore.cpp:1755]
UE4Editor_CoreUObject!UObject::ProcessInternal() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\coreuobject\private\uobject\scriptcore.cpp:698]
UE4Editor_CoreUObject!UFunction::Invoke() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\coreuobject\private\uobject\class.cpp:4195]
UE4Editor_CoreUObject!UObject::ProcessEvent() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\coreuobject\private\uobject\scriptcore.cpp:1050]
UE4Editor_Engine!AActor::ProcessEvent() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\engine\private\actor.cpp:580]
UE4Editor_Engine!AActor::BeginPlay() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\engine\private\actor.cpp:2780]
UE4Editor_Engine!AWorldSettings::NotifyBeginPlay() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\engine\private\worldsettings.cpp:132]
UE4Editor_Engine!AGameMode::HandleMatchHasStarted() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\engine\private\gamemode.cpp:605]
UE4Editor_Engine!AGameMode::SetMatchState() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\engine\private\gamemode.cpp:721]
UE4Editor_Engine!AGameMode::StartMatch() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\engine\private\gamemode.cpp:582]
UE4Editor_Engine!UWorld::BeginPlay() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\engine\private\world.cpp:3050]
UE4Editor_Engine!UGameInstance::StartPIEGameInstance() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\engine\private\gameinstance.cpp:273]
UE4Editor_UnrealEd!UEditorEngine::CreatePIEGameInstance() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\playlevel.cpp:3137]
UE4Editor_UnrealEd!UEditorEngine::PlayInEditor() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\playlevel.cpp:2385]
UE4Editor_UnrealEd!UEditorEngine::StartQueuedPlayMapRequest() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\playlevel.cpp:1066]
UE4Editor_UnrealEd!UEditorEngine::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\editorengine.cpp:1244]
UE4Editor_UnrealEd!UUnrealEdEngine::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\unrealedengine.cpp:366]
UE4Editor!FEngineLoop::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\launch\private\launchengineloop.cpp:2428]
UE4Editor!GuardedMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\launch\private\launch.cpp:142]
UE4Editor!GuardedMainWrapper() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\launch\private\windows\launchwindows.cpp:200]

Community References

Health bar not updating

Major Crash (Reproduced!) in UE4.9

Landscape material not height blended correctly

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Fixed

Component	UE - Editor - UI Systems
Affects Versions	4.9.1
Target Fix	4.10

Fix Commit	2708011
Release Commit	2713524

Created	Sep 25, 2015
Resolved	Sep 28, 2015
Updated	Jun 23, 2016

UE-21493

Scroll widget into view will cause a crash is given a null value

Scroll widget into view will cause a crash is given a null value

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