Engine crashes on adding variable to parent blueprint

In my project I have a parent blueprint with several child blueprints and some of them also have their own child blueprints. Every time I add a variable to this parent blueprint then compile the engine crashes and I’m given this error.

LoginId:d31b05ae46bdb0c062edbf82d96fe8fe
EpicAccountId:0e57fa0546b94ddcb19003630b820a53

Assertion failed: ContainerPtr [File:D:\Build++UE4+Release-4.15+Compile\Sync\Engine\Source\Runtime\CoreUObject\Public\UObject/UnrealType.h] [Line: 321]

UE4Editor_Core!FDebug::AssertFailed() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\core\private\misc\assertionmacros.cpp:349]
UE4Editor_CoreUObject!UObject::CallFunction() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\coreuobject\private\uobject\scriptcore.cpp:811]
UE4Editor_CoreUObject!UObject::execVirtualFunction() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\coreuobject\private\uobject\scriptcore.cpp:2255]
UE4Editor_CoreUObject!UObject::ProcessContextOpcode() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\coreuobject\private\uobject\scriptcore.cpp:2149]
UE4Editor_CoreUObject!UObject::ProcessInternal() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\coreuobject\private\uobject\scriptcore.cpp:948]
UE4Editor_CoreUObject!UObject::CallFunction() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\coreuobject\private\uobject\scriptcore.cpp:845]
UE4Editor_CoreUObject!UObject::ProcessInternal() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\coreuobject\private\uobject\scriptcore.cpp:948]
UE4Editor_CoreUObject!UFunction::Invoke() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\coreuobject\private\uobject\class.cpp:4525]
UE4Editor_CoreUObject!UObject::ProcessEvent() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\coreuobject\private\uobject\scriptcore.cpp:1318]
UE4Editor_Engine!AActor::ProcessEvent() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\engine\private\actor.cpp:678]
UE4Editor_Engine!AActor::UserConstructionScript()
UE4Editor_Engine!AActor::ProcessUserConstructionScript() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\engine\private\actorconstruction.cpp:841]
UE4Editor_Engine!AActor::ExecuteConstruction() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\engine\private\actorconstruction.cpp:757]
UE4Editor_UnrealEd!FActorReplacementHelper::Finalize() [d:\build++ue4+release-4.15+compile\sync\engine\source\editor\unrealed\private\kismet2\kismetreinstanceutilities.cpp:1207]
UE4Editor_UnrealEd!FBlueprintCompileReinstancer::ReplaceInstancesOfClass_Inner() [d:\build++ue4+release-4.15+compile\sync\engine\source\editor\unrealed\private\kismet2\kismetreinstanceutilities.cpp:1952]
UE4Editor_UnrealEd!FBlueprintCompileReinstancer::ReplaceInstancesOfClass() [d:\build++ue4+release-4.15+compile\sync\engine\source\editor\unrealed\private\kismet2\kismetreinstanceutilities.cpp:1476]
UE4Editor_UnrealEd!FBlueprintCompileReinstancer::ReinstanceInner() [d:\build++ue4+release-4.15+compile\sync\engine\source\editor\unrealed\private\kismet2\kismetreinstanceutilities.cpp:682]
UE4Editor_UnrealEd!FBlueprintCompileReinstancer::ReinstanceObjects() [d:\build++ue4+release-4.15+compile\sync\engine\source\editor\unrealed\private\kismet2\kismetreinstanceutilities.cpp:913]
UE4Editor_UnrealEd!FKismetEditorUtilities::CompileBlueprint() [d:\build++ue4+release-4.15+compile\sync\engine\source\editor\unrealed\private\kismet2\kismet2.cpp:868]
UE4Editor_Kismet!FBlueprintEditor::Compile() [d:\build++ue4+release-4.15+compile\sync\engine\source\editor\kismet\private\blueprinteditor.cpp:3283]
UE4Editor_Kismet!TBaseSPMethodDelegateInstance<0,FBlueprintEditor,0,TTypeWrapper __cdecl(void)>::Execute() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:327]
UE4Editor_Kismet!TBaseSPMethodDelegateInstance<0,FBlueprintEditor,0,void __cdecl(void)>::ExecuteIfSafe() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:433]
UE4Editor_Slate!FUICommandList::ExecuteAction() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\slate\private\framework\commands\uicommandlist.cpp:97]
UE4Editor_Slate!SToolBarButtonBlock::OnClicked() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\slate\private\framework\multibox\stoolbarbuttonblock.cpp:305]
UE4Editor_Slate!TMemberFunctionCaller::operator()<>() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\core\public\delegates\delegateinstanceinterface.h:165]
UE4Editor_Slate!TTupleImpl >::ApplyAfter >() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\core\public\delegates\tuple.h:134]
UE4Editor_Slate!TBaseSPMethodDelegateInstance<0,SToolBarButtonBlock,0,FReply __cdecl(void)>::Execute() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:327]
UE4Editor_Slate!TBaseDelegate::Execute() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\core\public\delegates\delegatesignatureimpl.inl:537]
UE4Editor_Slate!SButton::OnMouseButtonUp() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\slate\private\widgets\input\sbutton.cpp:278]
UE4Editor_Slate!::operator()() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5075]
UE4Editor_Slate!FEventRouter::Route >() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:238]
UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5064]
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5531]
UE4Editor_Slate!FSlateApplication::OnMouseUp() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5508]
UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:1698]
UE4Editor_Core!FWindowsApplication::DeferMessage() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:2120]
UE4Editor_Core!FWindowsApplication::ProcessMessage() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:867]
UE4Editor_Core!FWindowsApplication::AppWndProc() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:714]
user32
user32
UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\core\private\windows\windowsplatformmisc.cpp:980]
UE4Editor!FEngineLoop::Tick() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\launch\private\launchengineloop.cpp:2977]
UE4Editor!GuardedMain() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\launch\private\launch.cpp:166]
UE4Editor!GuardedMainWrapper() [d:\build++ue4+release-4.15+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:134]
UE4Editor!WinMain() [d:\build++ue4+release-4.15+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:264]
kernel32
ntdll

Hello ,

I was unable to reproduce the issue you are experiencing. I have a couple of questions that will help me narrow down the issue you are experiencing:

  1. Are you able to reproduce this issue in a new project?
  2. If so could you provide a detailed list of steps so that I can reproduce this issue on our end?
  3. Does the crash occur if you add variables to the children?

Thanks!

Hello ,

We have not heard back from you in a few days, so we are marking this post as Resolved for tracking purposes. If you are still experiencing the issue you reported, please respond to this message with additional information and we will follow up.

Hello, sorry about the slow reply.

  1. The crash doesn’t happen in other projects.
  2. The crash happens when I add any variable and hit compile. However if I save before compiling the when I open the editor after the crash the new variable is there and working, but if I add or remove another variable then the crash happens again.
  3. The crash does happen in only some of the children blueprints when following the same steps.

Thanks

Could you send me the project where this issue is occurring? You can message me privately on the forums here:

Thanks, but the file is several GBs and I sort of forgot about the problem until now. I appear to have solved the problem by duplicating the parent blueprint then making the duplicate the parent of all of the child blueprints. I then deleted the old parent blueprint and replaced all references to the original parent in the children.