Unreal Engine Issues and Bug Tracker (UE-48966)

Description

This is a trending crash in the 4.17 release.
Update: also trending in the 4.18 release

User Descriptions

Importing new character
togled lighting modes on shaders
Changing attriubtes on a material
Was changing Material end node's blend mode from Translucent to Additive
Changing a material to a postprocess type after changing the material type to unlit and the box before that to translucent.
Set a material to be transparent instead of opaque

Source Context

 269       #if UCLASS_FAST_ISA_COMPARE_WITH_OUTERWALK || UCLASS_FAST_ISA_IMPL == UCLASS_ISA_OUTERWALK
  270       	bool UObjectBaseUtility::IsA( const UClass* SomeBase ) const
  271       	{
  272       		UE_CLOG(!SomeBase, LogObj, Fatal, TEXT("IsA(NULL) cannot yield meaningful results"));
  273       
  274       		UClass* ThisClass = GetClass();
  275       
  276       		bool bOldResult = false;
  277 ***** 		for ( UClass* TempClass=ThisClass; TempClass; TempClass=TempClass->GetSuperClass() )
  278       		{
  279       			if ( TempClass == SomeBase )
  280       			{
  281       				bOldResult = true;
  282       				break;
  283       			}
  284       		}

Steps to Reproduce

Search in crash reporter suggests this isn't happening anymore. Please reopen if evidence to the contrary is found.

Callstack

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

UE4Editor_CoreUObject!UObjectBaseUtility::IsA() [uobjectbaseutility.cpp:278]
UE4Editor_MaterialEditor!FMaterialEditor::NotifyPostChange() [materialeditor.cpp:3606]
UE4Editor_PropertyEditor!FPropertyNode::NotifyPostChange() [propertynode.cpp:2421]
UE4Editor_PropertyEditor!FPropertyValueImpl::ImportText() [propertyhandleimpl.cpp:558]
UE4Editor_PropertyEditor!FPropertyValueImpl::ImportText() [propertyhandleimpl.cpp:358]
UE4Editor_PropertyEditor!FPropertyValueImpl::SetValueAsString() [propertyhandleimpl.cpp:829]
UE4Editor_PropertyEditor!SPropertyEditorCombo::SendToObjects() [spropertyeditorcombo.cpp:252]
UE4Editor_PropertyEditor!SPropertyEditorCombo::OnComboSelectionChanged() [spropertyeditorcombo.cpp:192]
UE4Editor_PropertyEditor!TBaseSPMethodDelegateInstance<0,SPropertyEditorCombo,0,TTypeWrapper<void> __cdecl() [delegateinstancesimpl.h:327]
UE4Editor_PropertyEditor!TBaseSPMethodDelegateInstance<0,SPropertyEditorCombo,0,void __cdecl() [delegateinstancesimpl.h:434]
UE4Editor_PropertyEditor!TBaseDelegate<void,TSharedPtr<FString,0>,enum ESelectInfo::Type>::ExecuteIfBound() [delegatesignatureimpl.inl:624]
UE4Editor_PropertyEditor!SPropertyComboBox::OnSelectionChangedInternal() [spropertycombobox.cpp:114]
UE4Editor_PropertyEditor!TBaseSPMethodDelegateInstance<0,SPropertyComboBox,0,TTypeWrapper<void> __cdecl() [delegateinstancesimpl.h:327]
UE4Editor_PropertyEditor!TBaseSPMethodDelegateInstance<0,SPropertyComboBox,0,void __cdecl() [delegateinstancesimpl.h:434]
UE4Editor_PropertyEditor!TBaseDelegate<void,TSharedPtr<FString,0>,enum ESelectInfo::Type>::ExecuteIfBound() [delegatesignatureimpl.inl:624]
UE4Editor_PropertyEditor!SComboBox<TSharedPtr<FString,0> >::OnSelectionChanged_Internal() [scombobox.h:455]
UE4Editor_PropertyEditor!TBaseSPMethodDelegateInstance<0,SComboBox<TSharedPtr<FString,0> >,0,TTypeWrapper<void> __cdecl() [delegateinstancesimpl.h:327]
UE4Editor_PropertyEditor!TBaseSPMethodDelegateInstance<0,SComboBox<TSharedPtr<FString,0> >,0,void __cdecl() [delegateinstancesimpl.h:434]
UE4Editor_PropertyEditor!TBaseDelegate<void,TSharedPtr<FString,0>,enum ESelectInfo::Type>::ExecuteIfBound() [delegatesignatureimpl.inl:624]
UE4Editor_PropertyEditor!SListView<TSharedPtr<FString,0> >::Private_SignalSelectionChanged() [slistview.h:725]
UE4Editor_PropertyEditor!STableRow<TSharedPtr<FString,0> >::OnMouseButtonUp() [stablerow.h:474]
UE4Editor_Slate!<lambda_1002768c627006711ef2f351a87ec0e7>::operator() [slateapplication.cpp:5199]
UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FToLeafmostPolicy,FPointerEvent,<lambda_1002768c627006711ef2f351a87ec0e7> >() [slateapplication.cpp:232]
UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent() [slateapplication.cpp:5188]
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent() [slateapplication.cpp:5690]
UE4Editor_Slate!FSlateApplication::OnMouseUp() [slateapplication.cpp:5670]
UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() [windowsapplication.cpp:1718]
UE4Editor_Core!FWindowsApplication::DeferMessage() [windowsapplication.cpp:2161]
UE4Editor_Core!FWindowsApplication::ProcessMessage() [windowsapplication.cpp:881]
UE4Editor_Core!FWindowsApplication::AppWndProc() [windowsapplication.cpp:721]
user32!UserCallWinProcCheckWow()
user32!DispatchMessageWorker()
UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() [windowsplatformmisc.cpp:1009]
UE4Editor!FEngineLoop::Tick() [launchengineloop.cpp:3151]
UE4Editor!GuardedMain() [launch.cpp:166]
UE4Editor!GuardedMainWrapper() [launchwindows.cpp:134]
UE4Editor!WinMain() [launchwindows.cpp:210]
UE4Editor!__scrt_common_main_seh() [exe_common.inl:253]
kernel32!BaseThreadInitThunk()
ntdll!RtlUserThreadStart()

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Fixed

Component	UE - Rendering Architecture - Materials
Affects Versions	4.17, 4.18, 4.19
Target Fix	4.24

Created	Aug 29, 2017
Resolved	Oct 28, 2019
Updated	Nov 2, 2021

UE-48966

[CrashReport] FMaterialEditor::NotifyPostChange()

[CrashReport] FMaterialEditor::NotifyPostChange()

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