This is a longstanding and common UMG crash that has affected more than 200 users since at least the 4.15 release.
User Descriptions
Source Context
367 inline TBaseDelegate& operator=(const TBaseDelegate& Other) 368 { 369 if (&Other != this) 370 { 371 // this down-cast is OK! allows for managing invocation list in the base class without requiring virtual functions 372 TDelegateInstanceInterface* OtherInstance = Other.GetDelegateInstanceProtected(); 373 374 if (OtherInstance != nullptr) 375 { 376 OtherInstance->CreateCopy(*this); 377 } 378 else 379 { 380 ***** Unbind(); 381 } 382 } 383 384 return *this; 385 }
repro steps currently unknown
Access violation - code c0000005 (first/second chance not available) UE4Editor_UMG!TBaseDelegate<FMargin>::operator=() [delegatesignatureimpl.inl:381] UE4Editor_UMG!UCanvasPanelSlot::SetOffsets() [canvaspanelslot.cpp:190] UE4Editor_UMG!UCanvasPanelSlot::SynchronizeProperties() [canvaspanelslot.cpp:301] UE4Editor_CoreUObject!UObject::PostEditUndo() [obj.cpp:530] UE4Editor_UnrealEd!FTransaction::Apply() [editortransaction.cpp:506] UE4Editor_UnrealEd!UTransBuffer::Undo() [editortransaction.cpp:874] UE4Editor_Kismet!TBaseSPMethodDelegateInstance<0,FBlueprintEditor,0,TTypeWrapper<void> __cdecl() [delegateinstancesimpl.h:327] UE4Editor_Kismet!TBaseSPMethodDelegateInstance<0,FBlueprintEditor,0,void __cdecl() [delegateinstancesimpl.h:434] 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:324] UE4Editor_Slate!<lambda_2afcd964c763e269e2d1a63f3a72f846>::operator() [slateapplication.cpp:4771] UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FBubblePolicy,FKeyEvent,<lambda_2afcd964c763e269e2d1a63f3a72f846> >() [slateapplication.cpp:232] UE4Editor_Slate!FEventRouter::RouteAlongFocusPath<FEventRouter::FBubblePolicy,<lambda_2afcd964c763e269e2d1a63f3a72f846>,FKeyEvent>() [slateapplication.cpp:214] UE4Editor_Slate!FSlateApplication::ProcessKeyDownEvent() [slateapplication.cpp:4769] UE4Editor_Slate!FSlateApplication::OnKeyDown() [slateapplication.cpp:4681] UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() [windowsapplication.cpp:1553] UE4Editor_Core!FWindowsApplication::DeferMessage() [windowsapplication.cpp:2161] UE4Editor_Core!FWindowsApplication::ProcessMessage() [windowsapplication.cpp:881] UE4Editor_Core!FWindowsApplication::AppWndProc() [windowsapplication.cpp:721] user32!UserCallWinProcCheckWow() user32!DispatchMessageWorker() UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() [windowsplatformmisc.cpp:1009] UE4Editor!FEngineLoop::Tick() [launchengineloop.cpp:3151] 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()
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