Unreal Engine Issues and Bug Tracker (UE-34265)

Description

Undo, redo, undo after issuing a replace actor action causes the editor to crash.

Found on: //UE4/Release-4.13 CL-3078131

Crash reporter: [Link Removed]

Regression from //UE4/Release-4.12 CL-3053425 , will investigate range on request.
Does not reproduce in //UE4/Main CL-3078219.
Does not reproduce in //UE4/Dev-Blueprints CL-3078965.

Steps to Reproduce

Open UE4Editor.exe QAGAME
Place an instance of BP_Variable into the world
Alt+Drag to duplicate BP_Variable
Select both instances of BP_Variable
Search for ContextMesh in the content browser
Select it in the content browser
Right click on one of the two instances of BP_Variable
Replace Instances with ContextMesh
Undo
Redo
Undo

Result: Crash

Callstack

MachineId:93621A354124D3DA0CD87BB8C7BF4324
EpicAccountId:a93319c1a68241d295f2574a4ba3da59

Assertion failed: Pair != nullptr [File:D:\Release-4.13\Engine\Source\Runtime\Core\Public\Containers\Map.h] [Line: 522] 



UE4Editor_Core!FDebug::AssertFailed() [d:\release-4.13\engine\source\runtime\core\private\misc\outputdevice.cpp:421]
UE4Editor_Engine!AActor::RerunConstructionScripts() [d:\release-4.13\engine\source\runtime\engine\private\actorconstruction.cpp:551]
UE4Editor_Engine!AActor::PostEditChangeProperty() [d:\release-4.13\engine\source\runtime\engine\private\actoreditor.cpp:105]
UE4Editor_CoreUObject!UObject::PostEditUndo() [d:\release-4.13\engine\source\runtime\coreuobject\private\uobject\obj.cpp:482]
UE4Editor_CoreUObject!UObject::PostEditUndo() [d:\release-4.13\engine\source\runtime\coreuobject\private\uobject\obj.cpp:486]
UE4Editor_Engine!AActor::PostEditUndo() [d:\release-4.13\engine\source\runtime\engine\private\actoreditor.cpp:445]
UE4Editor_UnrealEd!FTransaction::Apply() [d:\release-4.13\engine\source\editor\unrealed\private\editortransaction.cpp:488]
UE4Editor_UnrealEd!UTransBuffer::Undo() [d:\release-4.13\engine\source\editor\unrealed\private\editortransaction.cpp:855]
UE4Editor_UnrealEd!UEditorEngine::Exec_Transaction() [d:\release-4.13\engine\source\editor\unrealed\private\editorserver.cpp:5081]
UE4Editor_UnrealEd!UEditorEngine::Exec() [d:\release-4.13\engine\source\editor\unrealed\private\editorserver.cpp:5527]
UE4Editor_UnrealEd!UUnrealEdEngine::Exec() [d:\release-4.13\engine\source\editor\unrealed\private\unrealedsrv.cpp:624]
UE4Editor_MainFrame!FMainFrameActionCallbacks::ExecuteExecCommand() [d:\release-4.13\engine\source\editor\mainframe\private\frame\mainframeactions.cpp:925]
UE4Editor_MainFrame!TBaseStaticDelegateInstance<void __cdecl(void),FString>::ExecuteIfSafe() [d:\release-4.13\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:1017]
UE4Editor_Slate!FUICommandList::ConditionalProcessCommandBindings() [d:\release-4.13\engine\source\runtime\slate\private\framework\commands\uicommandlist.cpp:211]
UE4Editor_Slate!FUICommandList::ProcessCommandBindings() [d:\release-4.13\engine\source\runtime\slate\private\framework\commands\uicommandlist.cpp:155]
UE4Editor_MainFrame!FMainFrameActionCallbacks::OnUnhandledKeyDownEvent() [d:\release-4.13\engine\source\editor\mainframe\private\frame\mainframeactions.cpp:176]
UE4Editor_MainFrame!TTupleImpl<TIntegerSequence<unsigned int> >::ApplyAfter<FReply (__cdecl*const & __ptr64)(FKeyEvent const & __ptr64),FKeyEvent const & __ptr64>() [d:\release-4.13\engine\source\runtime\core\public\delegates\tuple.h:115]
UE4Editor_MainFrame!TBaseStaticDelegateInstance<FReply __cdecl(FKeyEvent const & __ptr64)>::Execute() [d:\release-4.13\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:948]
UE4Editor_Slate!TBaseDelegate<FReply,FKeyEvent const & __ptr64>::Execute() [d:\release-4.13\engine\source\runtime\core\public\delegates\delegatesignatureimpl.inl:521]
UE4Editor_Slate!FSlateApplication::ProcessKeyDownEvent() [d:\release-4.13\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4528]
UE4Editor_Slate!FSlateApplication::OnKeyDown() [d:\release-4.13\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4430]
UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() [d:\release-4.13\engine\source\runtime\core\private\windows\windowsapplication.cpp:1419]
UE4Editor_Core!FWindowsApplication::DeferMessage() [d:\release-4.13\engine\source\runtime\core\private\windows\windowsapplication.cpp:1930]
UE4Editor_Core!FWindowsApplication::ProcessMessage() [d:\release-4.13\engine\source\runtime\core\private\windows\windowsapplication.cpp:747]
UE4Editor_Core!FWindowsApplication::AppWndProc() [d:\release-4.13\engine\source\runtime\core\private\windows\windowsapplication.cpp:669]
user32
user32
UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() [d:\release-4.13\engine\source\runtime\core\private\windows\windowsplatformmisc.cpp:905]
UE4Editor!FEngineLoop::Tick() [d:\release-4.13\engine\source\runtime\launch\private\launchengineloop.cpp:2788]
UE4Editor!GuardedMain() [d:\release-4.13\engine\source\runtime\launch\private\launch.cpp:156]
UE4Editor!GuardedMainWrapper() [d:\release-4.13\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() [d:\release-4.13\engine\source\runtime\launch\private\windows\launchwindows.cpp:202]
UE4Editor!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:255]
kernel32
ntdll

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Fixed

Component	Tools
Affects Versions	4.13
Target Fix	4.13

Fix Commit	3086735
Main Commit	3092051
Release Commit	3086735

Created	Aug 4, 2016
Resolved	Aug 11, 2016
Updated	May 2, 2018

View Jira Issue

UE-34265

Undo, Redo, Undoing a blueprint actor Replace action causes a crash

Undo, Redo, Undoing a blueprint actor Replace action causes a crash

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