This is a common crash occurring in the 4.16 release. It seems to be related to applying a material to a mesh that is being used in Foliage.
Crash Reports are spread out among many different CrashGroups. Here are a few:
User Descriptions
Source Context
916 void UObject::ConditionalPostLoad()
917 {
918 check(!GEventDrivenLoaderEnabled || !HasAnyFlags(RF_NeedLoad)); //@todoio Added this as "nicks rule"
919 // PostLoad only if the object needs it and has already been serialized
920 //@todoio note this logic should be unchanged compared to main
921 ***** if (HasAnyFlags(RF_NeedPostLoad))
922 {
923
924 check(IsInGameThread() || HasAnyFlags(RF_ClassDefaultObject|RF_ArchetypeObject) || IsPostLoadThreadSafe() || IsA(UClass::StaticClass()))
New Repro
Result: crash
Freq: 4 for 4
Old Repro
Result: crash
Freq: 2 out of 10
Access violation - code c0000005 (first/second chance not available) UE4Editor_CoreUObject!UObject::ConditionalPostLoad() [obj.cpp:922] UE4Editor_Engine!UHierarchicalInstancedStaticMeshComponent::BuildTreeIfOutdated() [hierarchicalinstancedstaticmesh.cpp:2384] UE4Editor_Foliage!TBaseRawMethodDelegateInstance<0,FFoliageMeshInfo,void __cdecl() [delegateinstancesimpl.h:648] UE4Editor_Engine!TBaseMulticastDelegate<void,FBoxSphereBounds const & __ptr64>::Broadcast() [delegatesignatureimpl.inl:937] UE4Editor_Engine!UStaticMesh::CalculateExtendedBounds() [staticmesh.cpp:2240] UE4Editor_Engine!UStaticMesh::Build() [staticmeshbuild.cpp:169] UE4Editor_Engine!UStaticMesh::PostEditChangeProperty() [staticmesh.cpp:1790] UE4Editor_StaticMeshEditor!FMeshMaterialsLayout::CallPostEditChange() [staticmesheditortools.cpp:2543] UE4Editor_StaticMeshEditor!FMeshMaterialsLayout::OnMaterialChanged() [staticmesheditortools.cpp:2093] UE4Editor_StaticMeshEditor!TBaseSPMethodDelegateInstance<0,FMeshMaterialsLayout,0,TTypeWrapper<void> __cdecl() [delegateinstancesimpl.h:327] UE4Editor_StaticMeshEditor!TBaseSPMethodDelegateInstance<0,FMeshMaterialsLayout,0,void __cdecl() [delegateinstancesimpl.h:434] UE4Editor_PropertyEditor!TBaseDelegate<void,UMaterialInterface * __ptr64,UMaterialInterface * __ptr64,int,bool>::ExecuteIfBound() [delegatesignatureimpl.inl:624] UE4Editor_PropertyEditor!FMaterialItemView::ReplaceMaterial() [propertycustomizationhelpers.cpp:829] UE4Editor_PropertyEditor!TBaseSPMethodDelegateInstance<0,FMaterialItemView,0,TTypeWrapper<void> __cdecl() [delegateinstancesimpl.h:327] UE4Editor_PropertyEditor!TBaseSPMethodDelegateInstance<0,FMaterialItemView,0,void __cdecl() [delegateinstancesimpl.h:434] UE4Editor_PropertyEditor!SPropertyEditorAsset::SetValue() [spropertyeditorasset.cpp:610] UE4Editor_PropertyEditor!TBaseSPMethodDelegateInstance<0,SPropertyEditorAsset,0,TTypeWrapper<void> __cdecl() [delegateinstancesimpl.h:327] UE4Editor_PropertyEditor!TBaseSPMethodDelegateInstance<0,SPropertyEditorAsset,0,void __cdecl() [delegateinstancesimpl.h:434] UE4Editor_PropertyEditor!SPropertyMenuAssetPicker::OnAssetSelected() [spropertymenuassetpicker.cpp:249] UE4Editor_PropertyEditor!TBaseSPMethodDelegateInstance<0,SPropertyMenuAssetPicker,0,TTypeWrapper<void> __cdecl() [delegateinstancesimpl.h:327] UE4Editor_PropertyEditor!TBaseSPMethodDelegateInstance<0,SPropertyMenuAssetPicker,0,void __cdecl() [delegateinstancesimpl.h:434] UE4Editor_ContentBrowser!SAssetView::AssetSelectionChanged() [sassetview.cpp:3620] UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SAssetView,0,TTypeWrapper<void> __cdecl() [delegateinstancesimpl.h:327] UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SAssetView,0,void __cdecl() [delegateinstancesimpl.h:434] UE4Editor_ContentBrowser!TBaseDelegate<void,TSharedPtr<FAssetViewItem,0>,enum ESelectInfo::Type>::ExecuteIfBound() [delegatesignatureimpl.inl:624] UE4Editor_ContentBrowser!SListView<TSharedPtr<FAssetViewItem,0> >::Private_SignalSelectionChanged() [slistview.h:735] UE4Editor_ContentBrowser!STableRow<TSharedPtr<FAssetViewItem,0> >::OnMouseButtonUp() [stablerow.h:476] UE4Editor_Slate!<lambda_8d0e9a1da76abd0a756a3a9d775f5ed1>::operator() [slateapplication.cpp:5049] UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FToLeafmostPolicy,FPointerEvent,<lambda_8d0e9a1da76abd0a756a3a9d775f5ed1> >() [slateapplication.cpp:239] UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent() [slateapplication.cpp:5038] UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent() [slateapplication.cpp:5515] UE4Editor_Slate!FSlateApplication::OnMouseUp() [slateapplication.cpp:5495] UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() [windowsapplication.cpp:1704] UE4Editor_Core!FWindowsApplication::DeferMessage() [windowsapplication.cpp:2127] UE4Editor_Core!FWindowsApplication::ProcessMessage() [windowsapplication.cpp:867] UE4Editor_Core!FWindowsApplication::AppWndProc() [windowsapplication.cpp:714] user32!UserCallWinProcCheckWow() user32!DispatchMessageWorker() UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() [windowsplatformmisc.cpp:1009] UE4Editor!FEngineLoop::Tick() [launchengineloop.cpp:3058] 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()
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-45854 in the post.