Unreal Engine Issues and Bug Tracker (UE-198045)

Description

From licensee:

We've recently encountered an issue where BeginPlay was called on an Actor while the World is being torn down. This seems to stem from flushing level streaming while it has levels that need to be made visible.

Steps to Reproduce

To repro this, you need a world with a lot of level instances and you could add "ensure(!GetWorld()->bIsTearingDown)" to BeginPlay of some of the actors to help catch it:

Start PIE as Client. (Should be able to repro it in Standalone but I haven't tried it yet)
Run/fly around to cause level streaming to update.
End PIE or close the editor, without waiting in one place for too long so level streaming hasn't fully caught up yet.

Callstack

UnrealEditor-Engine.dll!AActor::DispatchBeginPlay(bool bFromLevelStreaming) Line 4115	C++
UnrealEditor-Engine.dll!ULevel::RouteActorInitialize(int NumActorsToProcess) Line 3382	C++
UnrealEditor-Engine.dll!UWorld::AddToWorld(ULevel * Level, const UE::Math::TTransform<double> & LevelTransform, bool bConsiderTimeLimit, FNetLevelVisibilityTransactionId TransactionId, ULevelStreaming * OwningLevelStreaming) Line 3018	C++
UnrealEditor-Engine.dll!ULevelStreaming::UpdateStreamingState(bool & bOutUpdateAgain, bool & bOutRedetermineTarget) Line 923	C++
[Inline Frame] UnrealEditor-Engine.dll!FStreamingLevelPrivateAccessor::UpdateStreamingState(ULevelStreaming *) Line 749	C++
UnrealEditor-Engine.dll!UWorld::UpdateLevelStreaming() Line 3897	C++
[Inline Frame] UnrealEditor-Engine.dll!UWorld::FlushLevelStreaming::__l2::<lambda_b56fe6bcc26432b93860da478b828a4f>::operator()() Line 4150	C++
UnrealEditor-Engine.dll!UWorld::FlushLevelStreaming(EFlushLevelStreamingType FlushType) Line 4166	C++
UnrealEditor-UnrealEd.dll!UEditorEngine::TeardownPlaySession(FWorldContext & PieWorldContext) Line 811	C++
UnrealEditor-UnrealEd.dll!UEditorEngine::EndPlayMap() Line 343	C++

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By Design

Component	UE - World Creation - Worldbuilding Tools
Target Fix	5.4

Created	Oct 16, 2023
Resolved	Oct 17, 2023
Updated	Nov 3, 2023

UE-198045

Flushing Level Streaming Can Trigger Actor Initialization during World Teardown

Flushing Level Streaming Can Trigger Actor Initialization during World Teardown

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