Unreal Engine Issues
Unreal Engine Issues
Niagara Mesh Renderer registers NumParticles x NumMeshVariants TLAS instances
UE - Rendering - Graphics Features - Ray Tracing - May 28, 2026When using the Niagara Mesh Renderer with multiple mesh variants selected via MeshIndex, the number of TLAS instances allocated is NumParticles × NumMeshVariants and enabling the Path Tracer can ca ...
Chaos Trailing Events not exposed to Blueprints and only accessible via Niagara Chaos DI
UE - Simulation - Visual - Apr 22, 2025Chaos Trailing Events not exposed to Blueprints and only accessible via Niagara Chaos DI. The licensee noticed that the Trailing event is not available to BPs. It's expected that the same data avail ...
Client Gameplay Effect stuck on due to duplicate ReplicationIDs
UE - Gameplay - Gameplay Ability System - Oct 31, 2025We've been tracking down a problem recently with the Gameplay Ability System where a gameplay effect is properly removed on the server, but the client has the gameplay effect stuck on permanently. ...
Editor Utility Widgets: Asset creating nodes' output pins in uber graphs cause asset deletion warning
UE - Framework - Blueprint Runtime - Oct 8, 2024Editor Utility Widgets (EUW) can be used to script editor behavior. One use case is the automation of asset creation. A licensee has reported that when an EUW is used to create an asset, for as lon ...
[AI] Gaps between Nav Mesh tiles in World Partition map causing movement issues
UE - AI - Navigation - Nov 4, 2025Navmesh has seams between some tiles that are actual edges rather than previously found "gaps" where it was a debug rendering issue. Pathfinding does fail between these tiles to go straight across. ...
In some situations, a Blueprint can become devoid of an Event Graph. While no graphs are present, multiple variables can be created with the same name.
UE - Framework - Blueprint Editor - Aug 26, 2024In some situations, a Blueprint can become devoid of an Event Graph, or be created without one from the start. For example, function "FKismetEditorUtilities::CreateBlueprint()" in UE 5.4 does not ca ...
FKeyHandle internal static atomic counter can overflow on long running games depending on usage pattern
UE - Anim - Sep 24, 2025Structure FKeyHandle stores an internal index, which is initialized from a static atomic counter in the default constructor: +----- FKeyHandle::FKeyHandle() { | static std::atomic<uint32> LastKey ...
Hot reload causes placed actor to lose variable references
UE - Foundation - Cpp Tools - Hot Reload - Nov 9, 2017Preforming a hot reload causes placed actors to lose code based variable settings. More repro steps: 1. Open UE4Editor.exe 2. Create a First Person Code project 3. Build the project for Developme ...
Given specific, non consistent, network connections, replication of some data can result in incorrect values
UE - Networking - Nov 2, 2016I appears to be possible to replicate a value and when the value gets to the client(s), it doesn't match what was sent from the server. In the project, ReplicatedActor is created by the Authority. ...
AddOrUpdateWarpTargetFromComponent behaving incorrectly when using a SceneComponent with non-identity scale
UE - Anim - Gameplay - Jul 15, 2025When using AddOrUpdateWarpTargetFromComponent you can pass in a SceneComponent, Relative Location and Rotation as well as optionally choosing to have the warp target follow the object if it moves.If ...