Unreal Engine Issues and Bug Tracker (UE-50696)

Description

A crash occurs when diffing a blueprint that contains an array that has changed from an Object Reference to a Soft Object Reference.

Note: I figured that this could be related to another bug that I entered, [Link Removed], but I tested this in a CL past the fix CL for that one in 4.18 Release and the issue still occurred.

Regression?: No
This was also tested in 4.16 and did not occur, but the test was not the same as the option for a Soft Object Reference array does not exist, only an Asset ID array. This is why this is not labeled as a regression.

Steps to Reproduce

Create a new project and add it to a Perforce repository.
Create a new Blueprint.
Add a Texture 2D Object Reference array to the new Blueprint, add 1 element and set that element to any texture.
Compile, save, and submit the blueprint to Perforce.
Change the Blueprint's Texture 2D array from an Object Reference to a Soft Object Reference.
Compile and Save the Blueprint, checking it out in the process.
Right-click the Blueprint in the Content Browser and select Diff Against Depot.
Result: The editor crashes with the callstack below
Expected: The diff window appears and shows what changes were made.

Callstack

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

UE4Editor_CoreUObject!UObjectPropertyBase::Identical() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\coreuobject\private\uobject\propertybaseobject.cpp:63]
UE4Editor_CoreUObject!UArrayProperty::Identical() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\coreuobject\private\uobject\propertyarray.cpp:52]
UE4Editor_Kismet!IdenticalHelper() [d:\build\++ue4+release-4.18+compile\sync\engine\source\editor\kismet\private\diffutils.cpp:436]
UE4Editor_Kismet!DiffUtils::Identical() [d:\build\++ue4+release-4.18+compile\sync\engine\source\editor\kismet\private\diffutils.cpp:604]
UE4Editor_Kismet!FDetailsDiff::DiffAgainst() [d:\build\++ue4+release-4.18+compile\sync\engine\source\editor\kismet\private\detailsdiff.cpp:124]
UE4Editor_Kismet!FCDODiffControl::FCDODiffControl() [d:\build\++ue4+release-4.18+compile\sync\engine\source\editor\kismet\private\sblueprintdiff.cpp:177]
UE4Editor_Kismet!SBlueprintDiff::GenerateDefaultsPanel() [d:\build\++ue4+release-4.18+compile\sync\engine\source\editor\kismet\private\sblueprintdiff.cpp:1378]
UE4Editor_Kismet!SBlueprintDiff::GenerateDifferencesList() [d:\build\++ue4+release-4.18+compile\sync\engine\source\editor\kismet\private\sblueprintdiff.cpp:1258]
UE4Editor_Kismet!SBlueprintDiff::Construct() [d:\build\++ue4+release-4.18+compile\sync\engine\source\editor\kismet\private\sblueprintdiff.cpp:737]
UE4Editor_AssetTools!TDecl<SBlueprintDiff,RequiredArgs::T0RequiredArgs>::operator<<=() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\slatecore\public\widgets\declarativesyntaxsupport.h:1091]
UE4Editor_AssetTools!FAssetTypeActions_Blueprint::PerformAssetDiff() [d:\build\++ue4+release-4.18+compile\sync\engine\source\developer\assettools\private\assettypeactions\assettypeactions_blueprint.cpp:254]
UE4Editor_AssetTools!UAssetToolsImpl::DiffAssets() [d:\build\++ue4+release-4.18+compile\sync\engine\source\developer\assettools\private\assettools.cpp:996]
UE4Editor_AssetTools!UAssetToolsImpl::DiffAgainstDepot() [d:\build\++ue4+release-4.18+compile\sync\engine\source\developer\assettools\private\assettools.cpp:968]
UE4Editor_ContentBrowser!FAssetContextMenu::ExecuteSCCDiffAgainstDepot() [d:\build\++ue4+release-4.18+compile\sync\engine\source\editor\contentbrowser\private\assetcontextmenu.cpp:2234]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<1,FAssetContextMenu,0,TTypeWrapper<void> __cdecl(void)>::Execute() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:327]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<1,FAssetContextMenu,0,void __cdecl(void)>::ExecuteIfSafe() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:434]
UE4Editor_Slate!SMenuEntryBlock::OnClicked() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\slate\private\framework\multibox\smenuentryblock.cpp:1091]
UE4Editor_Slate!SMenuEntryBlock::OnMenuItemButtonClicked() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\slate\private\framework\multibox\smenuentryblock.cpp:1042]
UE4Editor_Slate!TMemberFunctionCaller<SMenuEntryBlock,FReply (__cdecl SMenuEntryBlock::*)(void) __ptr64>::operator()<>() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\core\public\delegates\delegateinstanceinterface.h:165]
UE4Editor_Slate!UE4Tuple_Private::TTupleImpl<TIntegerSequence<unsigned int> >::ApplyAfter<TMemberFunctionCaller<SMenuEntryBlock,FReply (__cdecl SMenuEntryBlock::*)(void) __ptr64> >() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\core\public\templates\tuple.h:497]
UE4Editor_Slate!TBaseSPMethodDelegateInstance<0,SMenuEntryBlock,0,FReply __cdecl(void)>::Execute() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:327]
UE4Editor_Slate!TBaseDelegate<FReply>::Execute() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\core\public\delegates\delegatesignatureimpl.inl:537]
UE4Editor_Slate!SButton::OnMouseButtonUp() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\slate\private\widgets\input\sbutton.cpp:282]
UE4Editor_Slate!SMenuEntryButton::OnMouseButtonUp() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\slate\private\framework\multibox\smenuentryblock.cpp:439]
UE4Editor_Slate!<lambda_1002768c627006711ef2f351a87ec0e7>::operator()() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5264]
UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FToLeafmostPolicy,FPointerEvent,<lambda_1002768c627006711ef2f351a87ec0e7> >() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:234]
UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5253]
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5755]
UE4Editor_Slate!FSlateApplication::OnMouseUp() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5735]
UE4Editor_ApplicationCore!FWindowsApplication::ProcessDeferredMessage() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:1725]
UE4Editor_ApplicationCore!FWindowsApplication::DeferMessage() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:2171]
UE4Editor_ApplicationCore!FWindowsApplication::ProcessMessage() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:888]
UE4Editor_ApplicationCore!FWindowsApplication::AppWndProc() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:725]
user32
user32
UE4Editor_ApplicationCore!FWindowsPlatformApplicationMisc::PumpMessages() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsplatformapplicationmisc.cpp:129]
UE4Editor!FEngineLoop::Tick() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\launch\private\launchengineloop.cpp:3220]
UE4Editor!GuardedMain() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\launch\private\launch.cpp:166]
UE4Editor!GuardedMainWrapper() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:134]
UE4Editor!WinMain() [d:\build\++ue4+release-4.18+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

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Fixed

Component	UE - Gameplay - Blueprint Editor
Affects Versions	4.17, 4.18, 4.19
Target Fix	4.18

Fix Commit	3678388
Release Commit	3678388

Created	Oct 3, 2017
Resolved	Oct 3, 2017
Updated	Jul 2, 2018

View Jira Issue

UE-50696

Crash occurs when diffing blueprint that has had one of its variables changed to a Soft Object Reference

Crash occurs when diffing blueprint that has had one of its variables changed to a Soft Object Reference

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