Chaos Mover crash in standalone editor client

When using the Chaos Mover with resimulation enabled, standalone editor processes running as a client will crash around 80% of the time upon startup.

This can be reproduced using the Mover Examples plugin, in the “L_PhysicsSimulatedCharacter” map. See linked EPS case for repro project.

Set the following Physics Settings in the project’s DefaultEngine.ini:

[/Script/Engine.PhysicsSettings]
PhysicsPrediction=(bEnablePhysicsPrediction=True,bEnablePhysicsHistoryCapture=False,MaxSupportedLatencyPrediction=1000.000000,ResimulationSettings=(bEnableResimulationErrorPositionThreshold=True,ResimulationErrorPositionThreshold=10.000000,bEnableResimulationErrorRotationThreshold=True,ResimulationErrorRotationThreshold=4.000000,bEnableResimulationErrorLinearVelocityThreshold=False,ResimulationErrorLinearVelocityThreshold=5.000000,bEnableResimulationErrorAngularVelocityThreshold=False,ResimulationErrorAngularVelocityThreshold=2.000000),PhysicsReplicationLODSettings=(bEnablePhysicsReplicationLOD=False,MinimumBaseDistance=200.000000,BaseDistanceRadiusMultiplier=0.750000,BaseDistancesForResimulationMode=0.250000,BaseDistancesForFullPrediction=0.800000,TimeOverDistance=0.150000))
bTickPhysicsAsync=True

Run both a server and a client as standalone editor processes, either by using the “Standalone Game” play mode or by setting “Run Under One Process” to false.

Start the server and client(s), and observe the client crashes.

[Exception thrown at 0x00007FFB837EAE17 (UnrealEditor-Chaos.dll) in UnrealEditor.exe: 0xC0000005: Access violation reading location 0xFFFFFFFFFFFFFFFF.]

> [Inline Frame] UnrealEditor-Chaos.dll!Chaos::TGeometryParticleHandleImp<double,3,1>::CastToRigidParticle() Line 1716 C++

UnrealEditor-Chaos.dll!Chaos::FPBDRigidsEvolutionBase::TestModeParticleDisabled(Chaos::TGeometryParticleHandleImp<double,3,1> * Particle) Line 1360 C++

UnrealEditor-Chaos.dll!Chaos::FPBDRigidsEvolutionBase::DisableParticle(Chaos::TGeometryParticleHandleImp<double,3,1> * Particle) Line 462 C++

UnrealEditor-Chaos.dll!Chaos::FPBDRigidsSolver::UnregisterObject::__l2::<lambda_1>::operator()() Line 973 C++

[Inline Frame] UnrealEditor-Chaos.dll!Chaos::ISimCallbackObject::PreSimulate_Internal() Line 118 C++

UnrealEditor-Chaos.dll!Chaos::FPBDRigidsSolver::ProcessPushedData_Internal(Chaos::FPushPhysicsData & PushData) Line 2187 C++

UnrealEditor-Chaos.dll!Chaos::FPhysicsSolverProcessPushDataTask::ProcessPushData() Line 144 C++

UnrealEditor-Chaos.dll!Chaos::FSolverTasksPTOnly::AdvanceSolver() Line 793 C++

UnrealEditor-Chaos.dll!Chaos::FPBDRigidsSolver::ConditionalApplyRewind_Internal() Line 2568 C++

UnrealEditor-Chaos.dll!Chaos::FPhysicsSolverRewindTask::RewindSolver() Line 199 C++

[Inline Frame] UnrealEditor-Chaos.dll!Chaos::FPhysicsSolverRewindTask::DoTask(ENamedThreads::Type) Line 191 C++

UnrealEditor-Chaos.dll!TGraphTask<Chaos::FPhysicsSolverRewindTask>::ExecuteTask() Line 703 C++

UnrealEditor-Chaos.dll!UE::Tasks::Private::FTaskBase::TryExecuteTask() Line 524 C++

[Inline Frame] UnrealEditor-Chaos.dll!UE::Tasks::Private::FTaskBase::Init::__l2::<lambda_1>::operator()() Line 186 C++

[Inline Frame] UnrealEditor-Chaos.dll!LowLevelTasks::FTask::Init::__l15::<lambda_1>::operator()(const bool) Line 495 C++

[Inline Frame] UnrealEditor-Chaos.dll!Invoke(LowLevelTasks::FTask::Init::__l15::<lambda_1> &) Line 46 C++

[Inline Frame] UnrealEditor-Chaos.dll!LowLevelTasks::TTaskDelegate<LowLevelTasks::FTask * __cdecl(bool),48>::TTaskDelegateImpl<`LowLevelTasks::FTask::Init<`UE::Tasks::Private::FTaskBase::Init'::`2'::<lambda_1>>'::`15'::<lambda_1>,0>::Call(void *) Line 162 C++

UnrealEditor-Chaos.dll!LowLevelTasks::TTaskDelegate<LowLevelTasks::FTask * __cdecl(bool),48>::TTaskDelegateImpl<`LowLevelTasks::FTask::Init<`UE::Tasks::Private::FTaskBase::Init'::`2'::<lambda_1>>'::`15'::<lambda_1>,0>::CallAndMove(LowLevelTasks::TTaskDelegate<LowLevelTasks::FTask * __cdecl(bool),48> & Destination, void * InlineData, unsigned int DestInlineSize, bool <Params_0>) Line 171 C++

[Inline Frame] UnrealEditor-Core.dll!LowLevelTasks::TTaskDelegate<LowLevelTasks::FTask * __cdecl(bool),48>::CallAndMove(LowLevelTasks::TTaskDelegate<LowLevelTasks::FTask * __cdecl(bool),48> &) Line 309 C++

UnrealEditor-Core.dll!LowLevelTasks::FTask::ExecuteTask() Line 623 C++

UnrealEditor-Core.dll!LowLevelTasks::FScheduler::ExecuteTask(LowLevelTasks::FTask * InTask) Line 403 C++

[Inline Frame] UnrealEditor-Core.dll!LowLevelTasks::FScheduler::TryExecuteTaskFrom(LowLevelTasks::Private::FWaitEvent *) Line 704 C++

UnrealEditor-Core.dll!LowLevelTasks::FScheduler::WorkerLoop(LowLevelTasks::Private::FWaitEvent * WorkerEvent, LowLevelTasks::Private::TLocalQueueRegistry<1024,1024>::TLocalQueue * WorkerLocalQueue, unsigned int WaitCycles, bool bPermitBackgroundWork) Line 802 C++

[Inline Frame] UnrealEditor-Core.dll!LowLevelTasks::FScheduler::WorkerMain(LowLevelTasks::Private::FWaitEvent * WorkerEvent, LowLevelTasks::Private::TLocalQueueRegistry<1024,1024>::TLocalQueue * WorkerLocalQueue, unsigned int WaitCycles, bool) Line 861 C++

UnrealEditor-Core.dll!LowLevelTasks::FScheduler::CreateWorker::__l2::<lambda_1>::operator()() Line 223 C++

[Inline Frame] UnrealEditor-Core.dll!UE::Core::Private::Function::TFunctionRefBase<UE::Core::Private::Function::TFunctionStorage<1>,void __cdecl(void)>::operator()() Line 414 C++

UnrealEditor-Core.dll!FThreadImpl::Run() Line 69 C++

UnrealEditor-Core.dll!FRunnableThreadWin::Run() Line 167 C++

UnrealEditor-Core.dll!FRunnableThreadWin::GuardedRun() Line 79 C++

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