Incorrect NiagaraSystem passed to KillUnusedComponents in ReclaimWorldParticleSystem

UE - Rendering - Architecture - Niagara - Jun 10, 2025

In UNiagaraComponentPool::ReclaimWorldParticleSystem, the cleanup loop for WorldParticleSystemPools calls KillUnusedComponents with the reclaimed component's NiagaraSystem (Asset) instead of the sys ...

Staging a patch does not copy pak signatures when staging

UE - Core - Systems - Jun 10, 2025

When creating a patch with pak signing enabled the created output folder contains the pak files from the base release but does not contain the .sig files, even if they were enabled when creating the ...

Duplicated PCG Component instance resets overridden parameters to default

UE - Graphics Tools - PCG - Components - Jun 4, 2025

Context: Similar to parameters in the Material editor, PCG Graph Parameters are user created overridable values and can help create customizable graphs for a variety of situations. Problem: The l ...

Editor crashes when using PCG SpawnActor with a DataLayer inside a Level Instance

UE - Graphics Tools - PCG - Procedural Tools - Jun 4, 2025

A PCG actor is assigned to a DataLayer and placed inside a Level Instance. Then that Level Instance is placed into a World Partition map. When the SpawnActor node in the PCG graph is set to MergePCG ...

Niagara Scalability Crash When Processing Significance

UE - Rendering - Architecture - 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 ...

The selection operation with notify track in Persona is not compatible with custom window display scaling

UE - Runtime - Animation - Jun 4, 2025

It appears that notify track does not follow the size of the custom window scale. As a result, display problems may occur, and events may be placed in unexpected positions. This is similar to ...

Collision Drawing in Cooked Builds (Development) doesn't Show Geometry for Nanite Meshes

UE - Rendering - Features - Jun 2, 2025

Context The showFlag.CollisionVisibility 1 cvar is a viewport visualization mode that highlights which Actors will block visibility. The showFlag.CollisionPawn 1 cvar is a Player Collision viewmode ...

Crash in FShadowSceneRenderer::AddDirectionalLightShadow

UE - Rendering - Features - Shadows - Jun 2, 2025

This is a race condition between the FShadowScene update & rendering, where sometimes the renderer tries to access a data array before it has been populated leading to the crash. It happens fairly r ...

StructUtils plugin's `FInstancedStruct` in a CPP-defined struct in a `TArray` on an actor component defined in CPP and implemented in BP. Populating the instanced struct in an actor BP's class defaults breaks serialization of the class defaults.

UE - AI - May 30, 2025

Context Instanced structs are great for holding simple data with the main advantage they have is a low memory overhead unlike instanced objects. Problem The problem is in StructUtils plugin's `FIns ...

Crash in UPCGComponent::CleanupLocalImmediate(bool,bool) on file load

TM - Rendering - May 30, 2025

Reported in SF [Link Removed] User has a file that will crash at launch consistently. Crash report indicates the problem is with PCG content inside the file. ...