Description

The Editor will crash after adding more than 20 Emitters to a system.

Found in 4.20 CL# 4369336, 4.21 CL# 4753647, 4.22 CL# 6574378, 4.23 CL# 6599617

Steps to Reproduce
  1. Open the Editor
  2. Enable Niagara
  3. Create an Emitter and a System
  4. Add the Emitter to the System 21 times
  5. Try and save the emitter

Results:
Crash

Expected:
No Crash

Callstack
Assertion failed: InState >= ENiagaraExecutionState::Active && InState < ENiagaraExecutionState::Num [File:D:\Build\++UE4\Sync\Engine\Plugins\FX\Niagara\Source\Niagara\Private\NiagaraEmitterInstance.cpp] [Line: 1576]

UE4Editor_Core!FWindowsErrorOutputDevice::Serialize() [d:\build\++ue4\sync\engine\source\runtime\core\private\windows\windowserroroutputdevice.cpp:79]
UE4Editor_Core!FOutputDevice::LogfImpl() [d:\build\++ue4\sync\engine\source\runtime\core\private\misc\outputdevice.cpp:71]
UE4Editor_Core!FDebug::AssertFailed() [d:\build\++ue4\sync\engine\source\runtime\core\private\misc\assertionmacros.cpp:440]
UE4Editor_Core!FDebug::CheckVerifyFailedImpl() [d:\build\++ue4\sync\engine\source\runtime\core\private\misc\assertionmacros.cpp:418]
UE4Editor_Niagara!FNiagaraEmitterInstance::SetExecutionState() [d:\build\++ue4\sync\engine\plugins\fx\niagara\source\niagara\private\niagaraemitterinstance.cpp:1576]
UE4Editor_Niagara!FNiagaraSystemSimulation::Tick() [d:\build\++ue4\sync\engine\plugins\fx\niagara\source\niagara\private\niagarasystemsimulation.cpp:601]
UE4Editor_Niagara!FNiagaraSystemInstance::ComponentTick() [d:\build\++ue4\sync\engine\plugins\fx\niagara\source\niagara\private\niagarasysteminstance.cpp:1277]
UE4Editor_Niagara!UNiagaraComponent::TickComponent() [d:\build\++ue4\sync\engine\plugins\fx\niagara\source\niagara\private\niagaracomponent.cpp:419]
UE4Editor_Engine!FActorComponentTickFunction::ExecuteTickHelper<<lambda_04d8ef4b869923d6312932fb3543d049> >() [d:\build\++ue4\sync\engine\source\runtime\engine\classes\gameframework\actor.h:3109]
UE4Editor_Engine!FActorComponentTickFunction::ExecuteTick() [d:\build\++ue4\sync\engine\source\runtime\engine\private\components\actorcomponent.cpp:816]
UE4Editor_Engine!TGraphTask<FTickFunctionTask>::ExecuteTask() [d:\build\++ue4\sync\engine\source\runtime\core\public\async\taskgraphinterfaces.h:842]
UE4Editor_Core!FNamedTaskThread::ProcessTasksNamedThread() [d:\build\++ue4\sync\engine\source\runtime\core\private\async\taskgraph.cpp:686]
UE4Editor_Core!FNamedTaskThread::ProcessTasksUntilIdle() [d:\build\++ue4\sync\engine\source\runtime\core\private\async\taskgraph.cpp:593]
UE4Editor_Engine!FTickTaskSequencer::ReleaseTickGroup() [d:\build\++ue4\sync\engine\source\runtime\engine\private\ticktaskmanager.cpp:574]
UE4Editor_Engine!FTickTaskManager::RunTickGroup() [d:\build\++ue4\sync\engine\source\runtime\engine\private\ticktaskmanager.cpp:1505]
UE4Editor_Engine!UWorld::RunTickGroup() [d:\build\++ue4\sync\engine\source\runtime\engine\private\leveltick.cpp:789]
UE4Editor_Engine!UWorld::Tick() [d:\build\++ue4\sync\engine\source\runtime\engine\private\leveltick.cpp:1581]
UE4Editor_NiagaraEditor!FNiagaraSystemViewportClient::Tick() [d:\build\++ue4\sync\engine\plugins\fx\niagara\source\niagaraeditor\private\widgets\sniagarasystemviewport.cpp:92]
UE4Editor_UnrealEd!UEditorEngine::Tick() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\editorengine.cpp:1694]
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:3967]
UE4Editor!GuardedMain() [d:\build\++ue4\sync\engine\source\runtime\launch\private\launch.cpp:168]
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:275]
UE4Editor!__scrt_common_main_seh() [d:\agent\_work\3\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288]
kernel32
ntdll

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Fixed
ComponentRendering - Niagara
Affects Versions4.204.214.224.23
Target Fix4.23
Fix Commit6675144
CreatedMay 24, 2019
ResolvedMay 30, 2019
UpdatedJun 17, 2019