UUserWidget BP Editor crashes if adding variable

Development Programming & Scripting Blueprint
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1

The last crash could be solved by switching from 4.11 to 4.12 Preview 4, but now I’m getting the next one:
I’m adding this to my UUserWidget via C++:

UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Info")
float MaterialOnBelt;

After the first compile the variable shows up inside the widget blueprint, I can use Get and Set. But as soon as I click compile the editor crashes. After a restart, the whole variable disappears.

Crashlog:

MachineId:10056FE64E078C1ADEB3F88EEFA7A82A
EpicAccountId:8419be157f73487fa21e42da980afeaf

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

UE4Editor_CoreUObject!UObjectProperty::SerializeItem() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\coreuobject\private\uobject\propertyobject.cpp:40]
UE4Editor_CoreUObject!FPropertyTag::SerializeTaggedProperty() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\coreuobject\public\uobject\propertytag.h:168]
UE4Editor_CoreUObject!UStruct::SerializeTaggedProperties() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\coreuobject\private\uobject\class.cpp:1892]
UE4Editor_CoreUObject!UObject::SerializeScriptProperties() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\coreuobject\private\uobject\obj.cpp:1017]
UE4Editor_CoreUObject!UObject::Serialize() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\coreuobject\private\uobject\obj.cpp:956]
UE4Editor_UMG!UUserWidget::Serialize() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\umg\private\userwidget.cpp:1215]
UE4Editor_Engine!UEngine::CopyPropertiesForUnrelatedObjects() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\engine\private\unrealengine.cpp:11060]
UE4Editor_KismetCompiler!FKismetCompilerContext::Compile() [d:\build\++ue4+release-4.12+compile\sync\engine\source\editor\kismetcompiler\private\kismetcompiler.cpp:3470]
UE4Editor_UMGEditor!FWidgetBlueprintCompiler::Compile() [d:\build\++ue4+release-4.12+compile\sync\engine\source\editor\umgeditor\private\widgetblueprintcompiler.cpp:342]
UE4Editor_UMGEditor!FUMGEditorModule::Compile() [d:\build\++ue4+release-4.12+compile\sync\engine\source\editor\umgeditor\private\umgeditormodule.cpp:160]
UE4Editor_KismetCompiler!FKismet2CompilerModule::CompileBlueprintInner() [d:\build\++ue4+release-4.12+compile\sync\engine\source\editor\kismetcompiler\private\kismetcompilermodule.cpp:88]
UE4Editor_KismetCompiler!FKismet2CompilerModule::CompileBlueprint() [d:\build\++ue4+release-4.12+compile\sync\engine\source\editor\kismetcompiler\private\kismetcompilermodule.cpp:182]
UE4Editor_UnrealEd!FKismetEditorUtilities::CompileBlueprint() [d:\build\++ue4+release-4.12+compile\sync\engine\source\editor\unrealed\private\kismet2\kismet2.cpp:756]
UE4Editor_Kismet!FBlueprintEditor::Compile() [d:\build\++ue4+release-4.12+compile\sync\engine\source\editor\kismet\private\blueprinteditor.cpp:3184]
UE4Editor_Kismet!TBaseSPMethodDelegateInstance<0,FBlueprintEditor,0,TTypeWrapper<void> __cdecl(void)>::Execute() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:321]
UE4Editor_Kismet!TBaseSPMethodDelegateInstance<0,FBlueprintEditor,0,void __cdecl(void)>::ExecuteIfSafe() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:427]
UE4Editor_Slate!FUICommandList::ExecuteAction() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\commands\uicommandlist.cpp:87]
UE4Editor_Slate!SToolBarButtonBlock::OnClicked() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\multibox\stoolbarbuttonblock.cpp:300]
UE4Editor_Slate!TMemberFunctionCaller<SToolBarButtonBlock,FReply (__cdecl SToolBarButtonBlock::*)(void) __ptr64>::operator()<>() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\core\public\delegates\delegateinstanceinterface_variadics.h:161]
UE4Editor_Slate!TTupleImpl<TIntegerSequence<unsigned int> >::ApplyAfter_ExplicitReturnType<FReply,TMemberFunctionCaller<SToolBarButtonBlock,FReply (__cdecl SToolBarButtonBlock::*)(void) __ptr64> >() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\core\public\delegates\tuple.h:128]
UE4Editor_Slate!TBaseSPMethodDelegateInstance<0,SToolBarButtonBlock,0,FReply __cdecl(void)>::Execute() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:321]
UE4Editor_Slate!TBaseDelegate<FReply>::Execute() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\core\public\delegates\delegatesignatureimpl_variadics.inl:521]
UE4Editor_Slate!SButton::OnMouseButtonUp() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\widgets\input\sbutton.cpp:275]
UE4Editor_Slate!<lambda_8d0e9a1da76abd0a756a3a9d775f5ed1>::operator()() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4598]
UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FToLeafmostPolicy,FPointerEvent,<lambda_8d0e9a1da76abd0a756a3a9d775f5ed1> >() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:215]
UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4587]
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5041]
UE4Editor_Slate!FSlateApplication::OnMouseUp() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5021]
UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:1512]
UE4Editor_Core!FWindowsApplication::DeferMessage() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:1852]
UE4Editor_Core!FWindowsApplication::ProcessMessage() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:742]
UE4Editor_Core!FWindowsApplication::AppWndProc() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:664]
user32
user32
UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsplatformmisc.cpp:903]
UE4Editor!FEngineLoop::Tick() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\launch\private\launchengineloop.cpp:2728]
UE4Editor!GuardedMain() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\launch\private\launch.cpp:148]
UE4Editor!GuardedMainWrapper() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:200]
UE4Editor!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:264]
kernel32
ntdll
2

Hello,

  • Do you have the blueprint set to always save on compile?
  • Can you reproduce this in a clean project?
  • If so, can you please provide your repro steps?
3

Hi,

update to Preview 5 fixed the issue. No crash anymore :slight_smile: Thanks anyway!