Unreal Engine Issues and Bug Tracker (UE-28545)

Description

If two custom classes are created in C++ (Class A & B) and a reference to Class A is created as a member of Class B and initialized in Class B's constructor, the editor will crash once a blueprint of made of Class B

Note: This only occurs in 4.11 Preview 7 and in later changelists in the Releases branch. This issue does not occur in 4.12 (Main)

~~Regression?: Yes~~
~~Occurs: 2896623 (4.11 Preview 7)~~
~~Does not occur: 2872498 (4.10.4)~~
~~Have not tested earlier versions of the previews. If requested, can test earlier versions to narrow down the issue.~~
Not a regression

Steps to Reproduce

Create a new C++ project
Add two new C++ classes, one based on Actor named MyActor and the other based on Character named MyCharacter (It doesn't necessarily need to be these types, just for consistency)
In MyCharacter.h, add the following code at line #4:
```
 #include "MyActor.h" 
```
In MyCharacter.h, add the following code at line #27 (Under the declaration for SetupPlayerInputComponent)
```
 AMyActor* TheActor; 
```

In MyCharacter.cpp, add the following code at line #12:

 TheActor = CreateDefaultSubobject<AMyActor>(TEXT("TheActor"));

Compile the project and return to the editor
Create a blueprint based off MyCharacter
Result: The editor crashes with the callstack below
Expected: The blueprint should be created without an issue

Callstack

 Fatal error: [File:D:\BuildFarm\buildmachine_++UE4+Release-4.11\Engine\Source\Runtime\CoreUObject\Private\Templates\Casts.cpp] [Line: 11] 
Cast of MyCharacter /Script/TestingDetach.Default__MyCharacter to Level failed


UE4Editor_Core!FDebug::AssertFailed() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\runtime\core\private\misc\outputdevice.cpp:430]
UE4Editor_CoreUObject!CastLogError() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\runtime\coreuobject\private\templates\casts.cpp:12]
UE4Editor_Engine!CastChecked<ULevel,UObject>() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\runtime\coreuobject\public\templates\casts.h:195]
UE4Editor_Engine!TActorIteratorBase<FActorIterator>::operator++() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\runtime\engine\public\engineutils.h:253]
UE4Editor_Engine!UWorld::UpdateCullDistanceVolumes() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\runtime\engine\private\world.cpp:1390]
UE4Editor_Engine!UWorld::InitializeNewWorld() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\runtime\engine\private\world.cpp:1103]
UE4Editor_Engine!FPreviewScene::FPreviewScene() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\runtime\engine\private\previewscene.cpp:35]
UE4Editor_UnrealEd!FThumbnailPreviewScene::FThumbnailPreviewScene() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\editor\unrealed\private\thumbnailhelpers.cpp:28]
UE4Editor_UnrealEd!FClassActorThumbnailScene::FClassActorThumbnailScene() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\editor\unrealed\private\thumbnailhelpers.cpp:969]
UE4Editor_UnrealEd!FBlueprintThumbnailScene::FBlueprintThumbnailScene() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\editor\unrealed\private\thumbnailhelpers.cpp:1138]
UE4Editor_UnrealEd!UBlueprintThumbnailRenderer::CanVisualizeAsset() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\editor\unrealed\private\thumbnailrendering\blueprintthumbnailrenderer.cpp:22]
UE4Editor_UnrealEd!UThumbnailManager::GetRenderingInfo() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\editor\unrealed\private\thumbnailmanager.cpp:141]
UE4Editor_UnrealEd!FAssetThumbnailPool::Tick() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\editor\unrealed\private\assetthumbnail.cpp:944]
UE4Editor_UnrealEd!FTickableEditorObject::TickObjects() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\editor\unrealed\public\tickableeditorobject.h:15]
UE4Editor_UnrealEd!UEditorEngine::Tick() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\editor\unrealed\private\editorengine.cpp:1123]
UE4Editor_UnrealEd!UUnrealEdEngine::Tick() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\editor\unrealed\private\unrealedengine.cpp:370]
UE4Editor!FEngineLoop::Tick() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\runtime\launch\private\launchengineloop.cpp:2640]
UE4Editor!GuardedMain() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\runtime\launch\private\launch.cpp:142]
UE4Editor!GuardedMainWrapper() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() [d:\buildfarm\buildmachine_++ue4+release-4.11\engine\source\runtime\launch\private\windows\launchwindows.cpp:200]
UE4Editor!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:264]
kernel32
ntdll

Community References

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Fixed

Component	UE - Gameplay
Affects Versions	4.11
Target Fix	4.12

Fix Commit	2937852
Main Commit	3117035

Created	Mar 18, 2016
Resolved	Aug 29, 2016
Updated	Apr 27, 2018

View Jira Issue

UE-28545

Creating Actors as default subobjects causes crash (casting Outer to Level)

Creating Actors as default subobjects causes crash (casting Outer to Level)

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