Description

This is an infrequent but longstanding crash that has occurred since at least 4.13 and affected more than 350 users.

User Descriptions

  • I using widget bp. I Try moving blur mistake same time press ctrl + z and crash.
  • ?ctrl+z
  • move button out of vertical box using mouse
  • I do ctrl + Z at widget editor
  • I was resizing a button.
  • I was in widget blueprints, i actually had 2 opened. I tried dragging 3 components (a component within a component within a component, all selected) to the other blueprint. It actually seemed to work. But as soon as I tried to move the components, or remove one of these component, they were all messed up (they were either duplicating each other in each other, or just vanishing). So, worried about my work, I tried to ctrl-z my way back and that's when the segfault occured.

Source Context

 49       	if ( GetChildrenCount() > 0 )
   50       	{
   51       		Cast<UButtonSlot>(GetContentSlot())->BuildSlot(MyButton.ToSharedRef());
   52       	}
   53       	
   54       	return MyButton.ToSharedRef();
   55       }
   56       
   57       void UButton::SynchronizeProperties()
   58       {
   59       	Super::SynchronizeProperties();
   60       
   61 ***** 	MyButton->SetColorAndOpacity( ColorAndOpacity );
   62       	MyButton->SetBorderBackgroundColor( BackgroundColor );
   63       }
Steps to Reproduce

repro steps currently unknown, but clearly related to Undo in UMG

Callstack
Assertion failed: IsValid() [File:D:\Build\++UE4+Release-4.15+Compile\Sync\Engine\Source\Runtime\Core\Public\Templates/SharedPointer.h] [Line: 837]

UE4Editor_UMG!UButton::SynchronizeProperties() [button.cpp:62]
UE4Editor_UMG!UWidget::PostEditChangeProperty() [widget.cpp:800]
UE4Editor_CoreUObject!UObject::PostEditUndo() [obj.cpp:515]
UE4Editor_UnrealEd!FTransaction::Apply() [editortransaction.cpp:499]
UE4Editor_UnrealEd!UTransBuffer::Undo() [editortransaction.cpp:864]
UE4Editor_Kismet!TBaseSPMethodDelegateInstance<0,FBlueprintEditor,0,TTypeWrapper<void> __cdecl() [delegateinstancesimpl.h:327]
UE4Editor_Kismet!TBaseSPMethodDelegateInstance<0,FBlueprintEditor,0,void __cdecl() [delegateinstancesimpl.h:433]
UE4Editor_Slate!FUICommandList::ConditionalProcessCommandBindings() [uicommandlist.cpp:216]
UE4Editor_Slate!FUICommandList::ProcessCommandBindings() [uicommandlist.cpp:160]
UE4Editor_UnrealEd!FBaseToolkit::ProcessCommandBindings() [basetoolkit.cpp:74]
UE4Editor_UnrealEd!SStandaloneAssetEditorToolkitHost::OnKeyDown() [sstandaloneasseteditortoolkithost.cpp:338]
UE4Editor_Slate!<lambda_2afcd964c763e269e2d1a63f3a72f846>::operator() [slateapplication.cpp:4681]
UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FBubblePolicy,FKeyEvent,<lambda_2afcd964c763e269e2d1a63f3a72f846> >() [slateapplication.cpp:238]
UE4Editor_Slate!FEventRouter::RouteAlongFocusPath<FEventRouter::FBubblePolicy,<lambda_2afcd964c763e269e2d1a63f3a72f846>,FKeyEvent>() [slateapplication.cpp:220]
UE4Editor_Slate!FSlateApplication::ProcessKeyDownEvent() [slateapplication.cpp:4679]
UE4Editor_Slate!FSlateApplication::OnKeyDown() [slateapplication.cpp:4592]
UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() [windowsapplication.cpp:1533]
UE4Editor_Core!FWindowsApplication::DeferMessage() [windowsapplication.cpp:2120]
UE4Editor_Core!FWindowsApplication::ProcessMessage() [windowsapplication.cpp:867]
UE4Editor_Core!FWindowsApplication::AppWndProc() [windowsapplication.cpp:714]
user32!UserCallWinProcCheckWow()
user32!DispatchMessageWorker()
UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() [windowsplatformmisc.cpp:980]
UE4Editor!FEngineLoop::Tick() [launchengineloop.cpp:2977]
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()

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Won't Fix
ComponentTools - Editor - UMG
Affects Versions4.134.144.154.164.174.184.194.20
CreatedSep 7, 2017
ResolvedAug 18, 2021
UpdatedAug 18, 2021