Unreal Engine Issues
Unreal Engine Issues
Actor Component properties can become "linked" across multiple Blueprints after a hot reload
UE - Gameplay - Components - Dec 3, 2018If code in an Actor Component class is changed (eg. a new UPROPERTY is added) and a hot reload is performed to implement the changes, the properties in the component can become linked across any Blu ...
Niagara crash when using a particle attribute reader that has been passed around between modules
UE - Niagara - Oct 28, 2025The following Niagara usage pattern results in either a crash or in incorrect data being read from a Particle Attribute Reader: Emitter Spawn Stage – A module has an Attribute Reader input specifie ...
Linked animation graph doesn't trigger anim notifications on dedicated server.
OLD - Anim - Jun 15, 2020Linked animation graph doesn't trigger anim notifications on dedicated server. There is no expected message in log: LogBlueprintUserMessages: [HitReact_AnimBP_C_0] Client 0: HitNotify IsServer: tru ...
Properties not serialized when moving actor/component depending on unrelated specifiers
UE - Framework - Blueprint - Sep 25, 2023When an actor is moved on the level editor viewport, it is reconstructed along with its components, which at first makes their properties reset to their default state. Thankfully, this does not happ ...
Maximum number of State Machine connections?
OLD - Anim - Mar 16, 2015Adding more than 8 connections to or from a state in the state machine results in unpredictable behavior, like causing an animation to fail. (See image.) Was able to reproduce with user's test file ...
Scaled Geometry Collections result in a potential memory leak in Physics/ChaosUpdate
UE - Runtime - Simulation - Mar 30, 2025Scaled Geometry Collections (GC) result in a potential memory leak in Physics. Tracing the memory allocation of a single run of the Editor and multiple Play-In-Editor sessions of a scene that contai ...
Placed instances do not update dynamic binding after hot reload
UE - Foundation - Cpp Tools - Hot Reload - Oct 6, 2017Adding a dynamic binding and preforming a hot reload sometimes causes the binding to not be registered by class/blueprint instances that already exist in the world. Instances need to be replaced fr ...
Crumbling Geometry Collections do not render for one frame when child clusters crumble
UE - Runtime - Deformable - Oct 3, 2024Crumbling Geometry collection do not render for one frame when child clusters crumble. In the repro project a 4 particle GC is told to crumble. The single GeometryCollectionActor is then split into ...
Nativizing a blueprint interface using TMap/TSet causes Fatal error in UHT
UE - Gameplay - Blueprint Compiler - Sep 9, 2020FPropertyBase constructor does not handle a TMap/TSet property. Following workaround can avoid this error. explicit FPropertyBase(FProperty* Property) : PropertyExportFlags(PROPEXPORT_Public) ...
Mobile Previewer: Safe Zone Invalid Until Window Resize
UE - Platform - Mobile - Jul 12, 2021When the Mobile Previewer loads, the Safe Zone widget is not working properly at startup, and requires a window resize to update to the correct Safe Zone. ...