Unreal Engine Issues and Bug Tracker (UE-394309)

Description

A GC leak, similar to the one fixed by 44483919 but for Level Sequences in Level Instances rather than ones with Widgets.

A Level Sequence Actor in a Level Instance points to a Level Sequence Asset that has an Event Track that creates the Director when scrubbed over. If Sequencer is open at the same time as the Level Instance is open for edit, a strong reference is created to the Director which uses the Level Sequence Actor in the Level Instance as its outer. When the Level Instance is closed, the level is kept alive by sequencer. Tearing down the level triggers GC which finds the leak and fatal errors.

Steps to Reproduce

Steps to Reproduce

New blank project
New Basic World (/Game/BasicWorld)
New Empty World (/Game/EmptyWorld)
Add the Basic World as a level instance to the Empty World
Edit the Basic World level instance and add a Level Sequence Acotr
Create a level sequence asset for the player (/Game/LevelSequenceWithDirector)
Add an event track to the sequence
Add a key to the event track and double-click it to open the Director Blueprint
I added a PrintString node just to give it something substantial.
Compile and save and close the Director Blueprint editor
Save everything (because we're about to crash)
Open Sequencer and scrub over the event to create the Director.
"Cancel" the level instance edit
Crash

Callstack

[2026.08.26-07.49.46:778][295]LogLoad: Error: Printing reference chains leading to World /Game/BasicWorld.BasicWorld:

[2026.08.26-07.49.46:778][295]Error: (root) GCObjectReferencer /Engine/Transient.GCObjectReferencer_0

[2026.08.26-07.49.46:778][295]Error: -> FSequenceDirectorPlaybackCapability::AddReferencedObjects( LevelSequenceWithDirector_DirectorBP_C /Game/BasicWorld.BasicWorld:PersistentLevel.LevelSequenceActor_0.LevelSequenceWithDirector_Director_0)

[2026.08.26-07.49.46:788][295]Error: ^ UnknownFunction []

[2026.08.26-07.49.46:789][295]Error: ^ UnknownFunction []

[2026.08.26-07.49.46:790][295]Error: ^ UnknownFunction []

[2026.08.26-07.49.46:791][295]Error: ^ UnknownFunction []

[2026.08.26-07.49.46:792][295]Error: ^ UnknownFunction []

[2026.08.26-07.49.46:793][295]Error: ^ UnknownFunction []

[2026.08.26-07.49.46:794][295]Error: ^ UnknownFunction []

[2026.08.26-07.49.46:795][295]Error: ^ UnknownFunction []

[2026.08.26-07.49.46:796][295]Error: ^ UnknownFunction []

[2026.08.26-07.49.46:797][295]Error: ^ UnknownFunction []

[2026.08.26-07.49.46:799][295]Error: ^ UnknownFunction []

[2026.08.26-07.49.46:800][295]Error: ^ UnknownFunction []

[2026.08.26-07.49.46:801][295]Error: ^ UnknownFunction []

[2026.08.26-07.49.46:802][295]Error: ^ UnknownFunction []

[2026.08.26-07.49.46:803][295]Error: ^ UnknownFunction []

[2026.08.26-07.49.46:804][295]Error: ^ UnknownFunction []

[2026.08.26-07.49.46:805][295]Error: ^ UnknownFunction []

[2026.08.26-07.49.46:806][295]Error: ^ UnknownFunction []

[2026.08.26-07.49.46:806][295]Error: -> UObject* ULevelSequenceWithDirector_DirectorBP_C:: = (Garbage) LevelSequenceActor /Game/BasicWorld.BasicWorld:PersistentLevel.LevelSequenceActor_0

[2026.08.26-07.49.46:806][295]Error: -> UObject* ALevelSequenceActor:: = (Garbage) Level /Game/BasicWorld.BasicWorld:PersistentLevel

[2026.08.26-07.49.46:806][295]Error: -> UObject* ULevel:: = (Garbage) World /Game/BasicWorld.BasicWorld

[2026.08.26-07.49.46:806][295]Error:

[2026.08.26-07.49.46:822][295]LogLoad: Error: Old World /Game/BasicWorld.BasicWorld not cleaned up by GC! Object LevelSequenceActor /Game/BasicWorld.BasicWorld:PersistentLevel.LevelSequenceActor_0 is being referenced by LevelSequenceWithDirector_DirectorBP_C /Game/BasicWorld.BasicWorld:PersistentLevel.LevelSequenceActor_0.LevelSequenceWithDirector_Director_0:

(root) GCObjectReferencer /Engine/Transient.GCObjectReferencer_0

-> FSequenceDirectorPlaybackCapability::AddReferencedObjects( LevelSequenceWithDirector_DirectorBP_C /Game/BasicWorld.BasicWorld:PersistentLevel.LevelSequenceActor_0.LevelSequenceWithDirector_Director_0)

^ UnknownFunction []

-> UObject* ULevelSequenceWithDirector_DirectorBP_C:: = (Garbage) LevelSequenceActor /Game/BasicWorld.BasicWorld:PersistentLevel.LevelSequenceActor_0

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

^ This reference is preventing the old World from being GC'd ^

-> UObject* ALevelSequenceActor:: = (Garbage) Level /Game/BasicWorld.BasicWorld:PersistentLevel

-> UObject* ULevel:: = (Garbage) World /Game/BasicWorld.BasicWorld

[2026.08.26-07.49.46:823][295]LogLoad: Error: ====Fatal World Leaks====

Logging first error, check logs for additional information

(root) GCObjectReferencer /Engine/Transient.GCObjectReferencer_0

^ UnknownFunction []

-> UObject* ULevelSequenceWithDirector_DirectorBP_C:: = (Garbage) LevelSequenceActor /Game/BasicWorld.BasicWorld:PersistentLevel.LevelSequenceActor_0

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

^ This reference is preventing the old World from being GC'd ^

-> UObject* ALevelSequenceActor:: = (Garbage) Level /Game/BasicWorld.BasicWorld:PersistentLevel

-> UObject* ULevel:: = (Garbage) World /Game/BasicWorld.BasicWorld

====End Fatal World Leaks====

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Unresolved

Component	UE - ACT Character - Sequencer
Affects Versions	5.8

Created	Aug 31, 2026
Updated	Aug 31, 2026

View Jira Issue

UE-394309

Sequencer Crash (GC Leak) in Editor

Sequencer Crash (GC Leak) in Editor

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