Description

It seems that the crash is related to all of the "Write" events. I tested the Event ChaosDestruction Write, Event Float Write, and Event Bool Write and all 3 caused the crash, but their "Read" counterparts did not cause a crash. 

Creating an empty Niagara System and adding these doesn't cause a crash, so this only occurs when there is an emitter in the System.

Tested in //UE4/Release-4.25 @ CL 14469661 and this occurred, so not marking this bug as a Regression.

Steps to Reproduce
  1. Open a new project
  2. Create a new Niagara System with a Dynamic Beam emitter
  3. Add a Scratch Pad Module to System Update
  4. In the Scratch Pad graph, add an Event Bool Write node
  5. Connect the node to the InputMap and MapSet nodes
  6. Press the Apply button

RESULT:

The engine crashes

EXPECTED:

The user would be able to add the Event Bool Write node without crashing

Callstack
Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\Build\++UE4\Sync\Engine\Source\Runtime\Core\Public\Containers/ArrayView.h] [Line: 191] 
Array index out of bounds: 437 from an array of size 0


[Callstack] 0x00007ffac64c3b19 KERNELBASE.dll!UnknownFunction []
[Callstack] 0x00007ffa6866d066 UE4Editor-Core.dll!ReportAssert() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Core\Private\Windows\WindowsPlatformCrashContext.cpp:1616]
[Callstack] 0x00007ffa686707a8 UE4Editor-Core.dll!FWindowsErrorOutputDevice::Serialize() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Core\Private\Windows\WindowsErrorOutputDevice.cpp:78]
[Callstack] 0x00007ffa6837e8cd UE4Editor-Core.dll!FOutputDevice::LogfImpl() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Core\Private\Misc\OutputDevice.cpp:61]
[Callstack] 0x00007ffa68315575 UE4Editor-Core.dll!AssertFailedImplV() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Core\Private\Misc\AssertionMacros.cpp:104]
[Callstack] 0x00007ffa68317620 UE4Editor-Core.dll!FDebug::CheckVerifyFailedImpl() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Core\Private\Misc\AssertionMacros.cpp:461]
[Callstack] 0x00007ffa4f9cc578 UE4Editor-VectorVM.dll!DispatchCheckVerify<void,<lambda_d6f51ebde1563f7d54157f1336e1c313> >() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Core\Public\Misc\AssertionMacros.h:165]
[Callstack] 0x00007ffa4f992b66 UE4Editor-VectorVM.dll!FBatchedWriteIndexedOutput::CopyConstantToOutput<float,float,0>() [D:\Build\++UE4\Sync\Engine\Source\Runtime\VectorVM\Private\VectorVM.cpp:3209]
[Callstack] 0x00007ffa4f998685 UE4Editor-VectorVM.dll!<lambda_066d89be679256fc91d65acb4f3cb5d9>::operator()() [D:\Build\++UE4\Sync\Engine\Source\Runtime\VectorVM\Private\VectorVM.cpp:2551]
[Callstack] 0x00007ffa4f9b4628 UE4Editor-VectorVM.dll!VectorVM::Exec() [D:\Build\++UE4\Sync\Engine\Source\Runtime\VectorVM\Private\VectorVM.cpp:2698]
[Callstack] 0x00007ffa4a9d5b3e UE4Editor-Niagara.dll!FNiagaraScriptExecutionContextBase::Execute() [D:\Build\++UE4\Sync\Engine\Plugins\FX\Niagara\Source\Niagara\Private\NiagaraScriptExecutionContext.cpp:165]
[Callstack] 0x00007ffa4aa1c3dc UE4Editor-Niagara.dll!FNiagaraSystemSimulation::UpdateSystemInstances() [D:\Build\++UE4\Sync\Engine\Plugins\FX\Niagara\Source\Niagara\Private\NiagaraSystemSimulation.cpp:1570]
[Callstack] 0x00007ffa4aa14859 UE4Editor-Niagara.dll!FNiagaraSystemSimulation::Tick_Concurrent() [D:\Build\++UE4\Sync\Engine\Plugins\FX\Niagara\Source\Niagara\Private\NiagaraSystemSimulation.cpp:1329]
[Callstack] 0x00007ffa4aa17280 UE4Editor-Niagara.dll!FNiagaraSystemSimulation::Tick_GameThread() [D:\Build\++UE4\Sync\Engine\Plugins\FX\Niagara\Source\Niagara\Private\NiagaraSystemSimulation.cpp:1023]
[Callstack] 0x00007ffa4a9eb235 UE4Editor-Niagara.dll!FNiagaraSystemInstance::ManualTick() [D:\Build\++UE4\Sync\Engine\Plugins\FX\Niagara\Source\Niagara\Private\NiagaraSystemInstance.cpp:2016]
[Callstack] 0x00007ffa4a7274b1 UE4Editor-Niagara.dll!UNiagaraComponent::TickComponent() [D:\Build\++UE4\Sync\Engine\Plugins\FX\Niagara\Source\Niagara\Private\NiagaraComponent.cpp:680]
[Callstack] 0x00007ffa64e50b43 UE4Editor-Engine.dll!FActorComponentTickFunction::ExecuteTickHelper<<lambda_1634216a1cfe6570ddb9ff9456c1b5fb> >() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Engine\Classes\GameFramework\Actor.h:3573]
[Callstack] 0x00007ffa64e85244 UE4Editor-Engine.dll!FActorComponentTickFunction::ExecuteTick() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Engine\Private\Components\ActorComponent.cpp:1014]
[Callstack] 0x00007ffa65ca297e UE4Editor-Engine.dll!FTickFunctionTask::DoTask() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Engine\Private\TickTaskManager.cpp:284]
[Callstack] 0x00007ffa65cab56f UE4Editor-Engine.dll!TGraphTask<FTickFunctionTask>::ExecuteTask() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Core\Public\Async\TaskGraphInterfaces.h:886]
[Callstack] 0x00007ffa6812ecdc UE4Editor-Core.dll!FNamedTaskThread::ProcessTasksNamedThread() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Core\Private\Async\TaskGraph.cpp:709]
[Callstack] 0x00007ffa6812f0ce UE4Editor-Core.dll!FNamedTaskThread::ProcessTasksUntilQuit() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Core\Private\Async\TaskGraph.cpp:601]
[Callstack] 0x00007ffa681408fd UE4Editor-Core.dll!FTaskGraphImplementation::WaitUntilTasksComplete() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Core\Private\Async\TaskGraph.cpp:1525]
[Callstack] 0x00007ffa65cc8464 UE4Editor-Engine.dll!FTickTaskSequencer::ReleaseTickGroup() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Engine\Private\TickTaskManager.cpp:564]
[Callstack] 0x00007ffa65ccedaa UE4Editor-Engine.dll!FTickTaskManager::RunTickGroup() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Engine\Private\TickTaskManager.cpp:1578]
[Callstack] 0x00007ffa653ead8f UE4Editor-Engine.dll!UWorld::RunTickGroup() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Engine\Private\LevelTick.cpp:782]
[Callstack] 0x00007ffa653f55f7 UE4Editor-Engine.dll!UWorld::Tick() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Engine\Private\LevelTick.cpp:1457]
[Callstack] 0x00007ffa4a11f46c UE4Editor-NiagaraEditor.dll!FNiagaraSystemViewportClient::Tick() [D:\Build\++UE4\Sync\Engine\Plugins\FX\Niagara\Source\NiagaraEditor\Private\Widgets\SNiagaraSystemViewport.cpp:102]
[Callstack] 0x00007ffa62e597bd UE4Editor-UnrealEd.dll!UEditorEngine::Tick() [D:\Build\++UE4\Sync\Engine\Source\Editor\UnrealEd\Private\EditorEngine.cpp:1793]
[Callstack] 0x00007ffa637750e6 UE4Editor-UnrealEd.dll!UUnrealEdEngine::Tick() [D:\Build\++UE4\Sync\Engine\Source\Editor\UnrealEd\Private\UnrealEdEngine.cpp:426]
[Callstack] 0x00007ff6c2709bc2 UE4Editor.exe!FEngineLoop::Tick() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Launch\Private\LaunchEngineLoop.cpp:4836]
[Callstack] 0x00007ff6c272117c UE4Editor.exe!GuardedMain() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Launch\Private\Launch.cpp:169]
[Callstack] 0x00007ff6c272125a UE4Editor.exe!GuardedMainWrapper() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:137]
[Callstack] 0x00007ff6c27352bd UE4Editor.exe!WinMain() [D:\Build\++UE4\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:268]
[Callstack] 0x00007ff6c2737fea UE4Editor.exe!__scrt_common_main_seh() [d:\agent\_work\5\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288]
[Callstack] 0x00007ffac6ec7c24 KERNEL32.DLL!UnknownFunction []
[Callstack] 0x00007ffac874d721 ntdll.dll!UnknownFunction []

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Cannot Reproduce
ComponentUE - Niagara
Affects Versions4.25.44.26.2
Target Fix4.27
CreatedMay 13, 2021
ResolvedJun 1, 2021
UpdatedJul 20, 2021