Description

Clients crash when being part of a Seamless Travel if there was an active particle system in the level that was spawned at runtime. If the travel is not seamless, the particle system is placed in the level prior to runtime, or if the particle system is not active, this crash does not occur.

Regression?: Yes
This does not occur in 4.21

Steps to Reproduce
  1. Download the attached project, unzip, and open it
  2. In Editor Preferences > Level Editor > Play: Disable "Use Single Process"
  3. Set "Editor Multiplayer Mode" to "Play as Client"
  4. Set "Number of Players" to 2
  5. Open Map 1
  6. Start the game in Standalone Game
  7. Ensure the Server's window has focus and press "T"
    Result: The host travels properly and the client freezes when the travel begins and crashes after a moment.
    Expected: The host and client travel to the second level properly.
Callstack
Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\Build\++UE4\Sync\Engine\Source\Runtime\Core\Public\Containers/Array.h] [Line: 611]

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_Engine!DispatchCheckVerify<void,<lambda_fb2ec2681c61b9348455fae425a23e30> >() [d:\build\++ue4\sync\engine\source\runtime\core\public\misc\assertionmacros.h:162]
UE4Editor_Engine!FParticleSystemWorldManager::RegisterComponent() [d:\build\++ue4\sync\engine\source\runtime\engine\private\particles\particlesystemmanager.cpp:317]
UE4Editor_Engine!UParticleSystemComponent::SetComponentTickEnabled() [d:\build\++ue4\sync\engine\source\runtime\engine\private\particles\particlecomponents.cpp:4864]
UE4Editor_Engine!UParticleSystemComponent::ActivateSystem() [d:\build\++ue4\sync\engine\source\runtime\engine\private\particles\particlecomponents.cpp:5906]
UE4Editor_Engine!UParticleSystemComponent::Activate() [d:\build\++ue4\sync\engine\source\runtime\engine\private\particles\particlecomponents.cpp:6179]
UE4Editor_Engine!UActorComponent::OnRegister() [d:\build\++ue4\sync\engine\source\runtime\engine\private\components\actorcomponent.cpp:753]
UE4Editor_Engine!USceneComponent::OnRegister() [d:\build\++ue4\sync\engine\source\runtime\engine\private\components\scenecomponent.cpp:679]
UE4Editor_Engine!UPrimitiveComponent::OnRegister() [d:\build\++ue4\sync\engine\source\runtime\engine\private\components\primitivecomponent.cpp:563]
UE4Editor_Engine!UParticleSystemComponent::OnRegister() [d:\build\++ue4\sync\engine\source\runtime\engine\private\particles\particlecomponents.cpp:3805]
UE4Editor_Engine!UActorComponent::ExecuteRegisterEvents() [d:\build\++ue4\sync\engine\source\runtime\engine\private\components\actorcomponent.cpp:1283]
UE4Editor_Engine!UActorComponent::RegisterComponentWithWorld() [d:\build\++ue4\sync\engine\source\runtime\engine\private\components\actorcomponent.cpp:1020]
UE4Editor_Engine!AActor::IncrementalRegisterComponents() [d:\build\++ue4\sync\engine\source\runtime\engine\private\actor.cpp:4355]
UE4Editor_Engine!AActor::RegisterAllComponents() [d:\build\++ue4\sync\engine\source\runtime\engine\private\actor.cpp:4254]
UE4Editor_Engine!AActor::Rename() [d:\build\++ue4\sync\engine\source\runtime\engine\private\actor.cpp:931]
UE4Editor_Engine!FSeamlessTravelHandler::Tick() [d:\build\++ue4\sync\engine\source\runtime\engine\private\world.cpp:5967]
UE4Editor_Engine!UEngine::TickWorldTravel() [d:\build\++ue4\sync\engine\source\runtime\engine\private\unrealengine.cpp:11776]
UE4Editor_Engine!UGameEngine::Tick() [d:\build\++ue4\sync\engine\source\runtime\engine\private\gameengine.cpp:1350]
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
ComponentUE - Niagara
Affects Versions4.224.23
Target Fix4.23
Fix Commit7616225
Main Commit7950723
Release Commit7616225
CreatedApr 16, 2019
ResolvedAug 12, 2019
UpdatedSep 19, 2021