Actors unrelated to the changelist being validated cause errors

UE - World Creation - Worldbuilding Tools - World Partition - Nov 22, 2023

When validating a changelist, unrelated errors to the changelist can appear. Here's an example of running the validation on a cl named "temp cl" which just contains a single actor "Cylinder". The A ...

Pre-UE5 serialized FVariant FVector data corruption when deserialized in UE5

UE - Framework - LWC - Jan 15, 2024

FVariant is a struct that implements a union of data types, including FVector. When assigning an FVariant an FVector value in engine versions UE 4.27 or earlier, the FVariant will deserialize incorr ...

Exception on missing fiile during GC in horde storage

UE - Foundation - Horde - Storage - May 7, 2025

During GC, if a file was manually deleted (but the storage system is still track), GC can erroneously fail (and never remove the reference). This causes a backup in GC, putting the whole algorithm i ...

ChaosCacheManager is not reproducing Trailing Events

UE - Simulation - Physics - Mar 28, 2025

ChaosCacheManager (CCM) is not reproducing Trailing Events. Particles set to track Trailing Events correctly follow the position of the trailing event when the Geometry Collection (GC) is physically ...

ChaosCacheManager is not recording the Observed GeometryCollections NotifyBreak states between level loading and will default to false if changed from Record to Play

UE - Simulation - Physics - Mar 28, 2025

ChaosCacheManager (CCM) is not recording the Observed GeometryCollections (GC) NotifyBreak states between level loading and will default to false if changed from Record to Play. AChaosCacheManager ...

ChaosCacheManager is not reproducing Collision Events the second time you Record and Play

UE - Simulation - Physics - Mar 28, 2025

ChaosCacheManager (CCM) is not reproducing Collision events the second time (and onwards) we record a Geometry Collection (GC) breaking session. Particles set to track Collision Events correctly fol ...

Deadlock in UPhysicalAnimationComponent::UpdatePhysicsEngineImp

UE - Simulation - Physics - Sep 13, 2023

Deadlock in Chaos during PIE; the main thread is in USkeletalMeshComponent::HandleExistingParallelEvaluationTask waiting for a task to complete, and a worker thread is running that task and is in US ...

Niagara Scalability Crash When Processing Significance

UE - Niagara - Jun 4, 2025

Method FNiagaraScalabilityManager::ProcessSignificance() iterates on indices from Context.SignificanceIndices and uses them to access the State and ManagedComponents arrays. It can then decide to cr ...

[Feature Request] CVars for HISMC

UE - World Creation - Worldbuilding Tools - Foliage - Jun 18, 2021

Currently some (if not all or most) foliage CVars affect both foliage and HISMC. It would be nice to split this so that users can change the values of one without affecting the other. ...

Force Feedback has incorrect duration on iOS devices

UE - Platform - Apple - Sep 16, 2024

The user also describes not being able to tell the difference between a force feedback value of 0.3 and 1,0 on iPhones Note: This is likely an issue somewhere in FIOSInputInterface::SetForceFeedb ...