Unreal Engine Issues and Bug Tracker (UE-45562)

Description

This report was logged due to a high volume of submitted crash reports. It occurs when opening a level where a deleted mesh as being used as foliage.

This is a regression. The crash does not occur in 4.15.3, instead it displays an error that the asset failed to load.

User Descriptions

I was trying to open my level in the new 4.16 after making a copy from the 4.15 version

Source Context

66       			}
   67       		}
   68       
   69       		return false;
   70       	}
   71       
   72       	/**
   73       	 * Removes all functions from this multi-cast delegate's invocation list that are bound to the specified UserObject.
   74       	 * Note that the order of the delegates may not be preserved!
   75       	 *
   76       	 * @param InUserObject The object to remove all delegates for.
   77       	 */
   78       	void RemoveAll( const void* InUserObject )
   79       	{
   80 ***** 		for (int32 InvocationListIndex = InvocationList.Num() - 1; InvocationListIndex >= 0; --InvocationListIndex)
   81       		{
   82       			FDelegateBase& DelegateBaseRef = InvocationList[InvocationListIndex];
   83       
   84       			IDelegateInstance* DelegateInstance = DelegateBaseRef.GetDelegateInstanceProtected();
   85       			if ((DelegateInstance != nullptr) && DelegateInstance->HasSameObject(InUserObject))
   86       			{
   87       				DelegateBaseRef.Unbind();
   88       			}
   89       		}

Steps to Reproduce

Create blank project with starter content
Create new Level and open it
Add a box or landscape to the level.
Add any mesh as Foliage and paint it on the box or landscape
Save the map and assets
Open any different level
In the Content Browser, delete the mesh that was used as foliage. Choose "Force Delete".
Re-open the first map

Result: Crash
Expected: Error message that the asset failed to load.

Callstack

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

UE4Editor_Foliage!FMulticastDelegateBase<FWeakObjectPtr>::RemoveAll() [multicastdelegatebase.h:81]
UE4Editor_Foliage!AInstancedFoliageActor::RemoveFoliageType() [instancedfoliage.cpp:2094]
UE4Editor_Foliage!AInstancedFoliageActor::PostLoad() [instancedfoliage.cpp:2622]
UE4Editor_CoreUObject!UObject::ConditionalPostLoad() [obj.cpp:952]
UE4Editor_CoreUObject!UObject::PostLoadSubobjects() [obj.cpp:985]
UE4Editor_CoreUObject!UObject::ConditionalPostLoad() [obj.cpp:941]
UE4Editor_CoreUObject!EndLoad() [uobjectglobals.cpp:1535]
UE4Editor_CoreUObject!LoadPackageInternal() [uobjectglobals.cpp:1289]
UE4Editor_CoreUObject!LoadPackage() [uobjectglobals.cpp:1377]
UE4Editor_CoreUObject!ResolveName() [uobjectglobals.cpp:778]
UE4Editor_CoreUObject!StaticLoadObjectInternal() [uobjectglobals.cpp:865]
UE4Editor_CoreUObject!StaticLoadObject() [uobjectglobals.cpp:929]
UE4Editor_ContentBrowser!FAssetData::GetAsset() [assetdata.h:250]
UE4Editor_ContentBrowser!SContentBrowser::OnAssetsActivated() [scontentbrowser.cpp:1873]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SContentBrowser,0,TTypeWrapper<void> __cdecl() [delegateinstancesimpl.h:327]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SContentBrowser,0,void __cdecl() [delegateinstancesimpl.h:434]
UE4Editor_ContentBrowser!TBaseDelegate<void,TArray<FAssetData,FDefaultAllocator> const & __ptr64,enum EAssetTypeActivationMethod::Type>::ExecuteIfBound() [delegatesignatureimpl.inl:624]
UE4Editor_ContentBrowser!SAssetView::OnListMouseButtonDoubleClick() [sassetview.cpp:3755]
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> >::ExecuteIfBound() [delegatesignatureimpl.inl:624]
UE4Editor_ContentBrowser!SListView<TSharedPtr<FAssetViewItem,0> >::Private_OnItemDoubleClicked() [slistview.h:815]
UE4Editor_ContentBrowser!STableRow<TSharedPtr<FAssetViewItem,0> >::OnMouseButtonDoubleClick() [stablerow.h:290]
UE4Editor_Slate!<lambda_eeb33fd1b480e3cad58a1531d90d2e14>::operator() [slateapplication.cpp:5460]
UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FBubblePolicy,FPointerEvent,<lambda_eeb33fd1b480e3cad58a1531d90d2e14> >() [slateapplication.cpp:239]
UE4Editor_Slate!FSlateApplication::RoutePointerDoubleClickEvent() [slateapplication.cpp:5458]
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonDoubleClickEvent() [slateapplication.cpp:5441]
UE4Editor_Slate!FSlateApplication::OnMouseDoubleClick() [slateapplication.cpp:5419]
UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() [windowsapplication.cpp:1708]
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:264]
kernel32!BaseThreadInitThunk()
ntdll!RtlUserThreadStart()

Community References

Editor crash when mesh used as folige is deleted

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Fixed

Component	UE - World Creation - Worldbuilding Tools - Foliage
Affects Versions	4.16
Target Fix	4.16.2

Fix Commit	3476060

Created	May 31, 2017
Resolved	Jun 6, 2017
Updated	May 9, 2020

UE-45562

Crash when opening level that uses foliage with a deleted mesh

Crash when opening level that uses foliage with a deleted mesh

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