Unreal Engine Issues and Bug Tracker (UE-46534)

Description

Attempting to call a blueprint event on a CDO object causes the editor to crash.

Regression:
Yes- Repro steps did not crash editor in binary 4.15.3 (CL 3450819)

Steps to Reproduce

Open UE4 Editor (third person template)

Add the following class declaration to ProjectNameCharacter.h above the character class declaration

UCLASS(Blueprintable)
class UMyBlueprintObject : public UObject
{
	GENERATED_BODY()
public:
	UMyBlueprintObject() {};

	UFUNCTION(BlueprintImplementableEvent, Category = "Foo")
		void Bar(UObject* SomeObject) const;

};

add the following code inside character class delcaration

	virtual void BeginPlay() override;

	UPROPERTY(EditAnywhere, Category = "Foobar")
		TSubclassOf<UMyBlueprintObject> DerivedBlueprintObject;

add the following to ProjectNameCharacter.cpp

void A[ProjectName]Character::BeginPlay()
{
	Super::BeginPlay();

	if (*DerivedBlueprintObject)
	{
		DerivedBlueprintObject->GetDefaultObject<UMyBlueprintObject>()->Bar(this);
	}
}

Compile
Open ProjectFolder/Config/DefaultEditorPerProjectUserSettings.ini

Add

ContentBrowserTab1.SelectedPaths=/Game/ThirdPersonCPP[DefaultEventNodes]+Node=(TargetClass=MyBlueprintObject TargetEvent="Bar")

Save and close ini file
Open project
Create blueprint based on MyBlueprintObject (TestBP)
Drag off of Bar event and add Print String node
Select the character in the level
In the details panel, search "obj" and set Derived Blueprint Object to TestBP
PIE

Result:
Editor crashes with provided callstack

Expected:
PIE session runs and print string message appears on screen

Callstack

LoginId:7156c35640f86204e61b8383f45dee17
EpicAccountId:e8c7fa630b6440f69a25a2c64d6c482c

Assertion failed: ContainerPtr [File:D:\Build\++UE4+Release-4.16+Compile\Sync\Engine\Source\Runtime\CoreUObject\Public\UObject/UnrealType.h] [Line: 324] 



UE4Editor_Core!FDebug::AssertFailed() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\core\private\misc\assertionmacros.cpp:349]
UE4Editor_CoreUObject!UObject::execLetValueOnPersistentFrame() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\coreuobject\private\uobject\scriptcore.cpp:1788]
UE4Editor_CoreUObject!UObject::ProcessInternal() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\coreuobject\private\uobject\scriptcore.cpp:943]
UE4Editor_CoreUObject!UFunction::Invoke() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\coreuobject\private\uobject\class.cpp:4461]
UE4Editor_CoreUObject!UObject::ProcessEvent() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\coreuobject\private\uobject\scriptcore.cpp:1313]
UE4Editor_CDOCrash_5003!UMyBlueprintObject::Bar()
UE4Editor_Engine!AActor::DispatchBeginPlay() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\engine\private\actor.cpp:3104]
UE4Editor_Engine!AWorldSettings::NotifyBeginPlay() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\engine\private\worldsettings.cpp:187]
UE4Editor_Engine!AGameStateBase::HandleBeginPlay() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\engine\private\gamestatebase.cpp:177]
UE4Editor_Engine!UWorld::BeginPlay() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\engine\private\world.cpp:3443]
UE4Editor_Engine!UGameInstance::StartPlayInEditorGameInstance() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\engine\private\gameinstance.cpp:338]
UE4Editor_UnrealEd!UEditorEngine::CreatePIEGameInstance() [d:\build\++ue4+release-4.16+compile\sync\engine\source\editor\unrealed\private\playlevel.cpp:3427]
UE4Editor_UnrealEd!UEditorEngine::PlayInEditor() [d:\build\++ue4+release-4.16+compile\sync\engine\source\editor\unrealed\private\playlevel.cpp:2515]
UE4Editor_UnrealEd!UEditorEngine::StartQueuedPlayMapRequest() [d:\build\++ue4+release-4.16+compile\sync\engine\source\editor\unrealed\private\playlevel.cpp:1217]
UE4Editor_UnrealEd!UEditorEngine::Tick() [d:\build\++ue4+release-4.16+compile\sync\engine\source\editor\unrealed\private\editorengine.cpp:1525]
UE4Editor_UnrealEd!UUnrealEdEngine::Tick() [d:\build\++ue4+release-4.16+compile\sync\engine\source\editor\unrealed\private\unrealedengine.cpp:386]
UE4Editor!FEngineLoop::Tick() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\launch\private\launchengineloop.cpp:3119]
UE4Editor!GuardedMain() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\launch\private\launch.cpp:166]
UE4Editor!GuardedMainWrapper() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:134]
UE4Editor!WinMain() [d:\build\++ue4+release-4.16+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:210]
UE4Editor!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:253]
kernel32
ntdll

Community References

No longer able to call Blueprint Events on CDOs

Editor crash when calling function on default object of blueprint child

4.17 Editor crashing during load, Cast of REINST to ActorComponent

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Fixed

Component	UE - Gameplay - Blueprint
Affects Versions	4.16.1
Target Fix	4.16.3, 4.17

Fix Commit	3525425
Main Commit	3555226
Release Commit	3525425

Created	Jun 27, 2017
Resolved	Jul 7, 2017
Updated	Apr 27, 2018

UE-46534

Cannot call blueprint events on CDO

Cannot call blueprint events on CDO

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