Unreal Engine Issues

UE-67332

Crash Upon Sequencer Modification of Actor's Array Variable

Crash Upon Sequencer Modification of Actor's Array Variable

Description

If Sequencer event track modifies an Actor's Integer Variable Array that is exposed to Cinematics, the Editor will crash when the Stop button is pressed.

Steps to Reproduce

Project Google Drive for easy replication.([Link Removed])

  1. Open Unreal Engine 4.21 -> Create Blank Blueprint Project.
  2. Create an Actor Blueprint named "Actor_BP".
  3. Inside of this Actor Blueprint create an Integer Array Variable
  4.  Add a single element to the Integer Array with a default value of 0.
  5. Expose the Array Variable to Cinematics.  Compile-Save
  6. Add this Bp_Actor to the World.
  7. Create a New Level Sequencer.
  8. Add a track for BP_Actor
  9. Add a track for BP_Actor's array variable.
  10. Add Level Sequencer to the world
  11. Back in editor, Simulate Play in Editor
  12. In the Level Sequencer, press play, and let the sequence finish
  13.  Back in editor, Click stop.

 

Result:  Crash

Expected:  The Property should have the same value assigned as the key, and the editor does not crash.

Callstack
UE4Editor_Core!rml::internal::isLargeObject<0>() [l:\dev\partner-intel\engine\source\thirdparty\inteltbb\inteltbb-4.4u3\src\tbbmalloc\frontend.cpp:2424]
UE4Editor_Core!rml::internal::internalFree() [l:\dev\partner-intel\engine\source\thirdparty\inteltbb\inteltbb-4.4u3\src\tbbmalloc\frontend.cpp:2594]
UE4Editor_Core!scalable_realloc() [l:\dev\partner-intel\engine\source\thirdparty\inteltbb\inteltbb-4.4u3\src\tbbmalloc\frontend.cpp:2898]
UE4Editor_Core!FMallocTBB::Realloc() [d:\build\++ue4\sync\engine\source\runtime\core\private\hal\malloctbb.cpp:123]
UE4Editor_Core!FMemory::Realloc() [d:\build\++ue4\sync\engine\source\runtime\core\public\hal\fmemory.inl:52]
UE4Editor_CoreUObject!FScriptArray::ResizeTo() [d:\build\++ue4\sync\engine\source\runtime\core\public\containers\scriptarray.h:200]
UE4Editor_CoreUObject!UArrayProperty::DestroyValueInternal() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\propertyarray.cpp:491]
UE4Editor_CoreUObject!UObject::DestroyNonNativeProperties() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\blueprint\blueprintsupport.cpp:2576]
UE4Editor_CoreUObject!UObject::FinishDestroy() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\obj.cpp:783]
UE4Editor_CoreUObject!UObject::ConditionalFinishDestroy() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\obj.cpp:980]
UE4Editor_CoreUObject!IncrementalPurgeGarbage() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\garbagecollection.cpp:1126]
UE4Editor_CoreUObject!CollectGarbageInternal() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\garbagecollection.cpp:1603]
UE4Editor_CoreUObject!CollectGarbage() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\garbagecollection.cpp:1676]
UE4Editor_UnrealEd!UEditorEngine::EndPlayMap() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\playlevel.cpp:468]
UE4Editor_UnrealEd!UEditorEngine::Tick() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\editorengine.cpp:1992]
UE4Editor_UnrealEd!UUnrealEdEngine::Tick() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\unrealedengine.cpp:403]
UE4Editor!FEngineLoop::Tick() [d:\build\++ue4\sync\engine\source\runtime\launch\private\launchengineloop.cpp:3699]
UE4Editor!GuardedMain() [d:\build\++ue4\sync\engine\source\runtime\launch\private\launch.cpp:174]
UE4Editor!GuardedMainWrapper() [d:\build\++ue4\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:145]
UE4Editor!WinMain() [d:\build\++ue4\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:276]
UE4Editor!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:283]
kernel32
ntdll

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Won't Do
ComponentUE - Anim - Sequencer
Affects Versions4.21, 4.22, 4.23
CreatedDec 7, 2018
ResolvedDec 18, 2020
UpdatedJan 7, 2021