Reference to control rig can be lost on actors with multiple skeletal mesh components

UE - Anim - Rigging - Control Rig - Apr 4, 2023

In the attached project, when we initially add a control rig track for the actor with multiple skeletal mesh components, we add the control rig for the correct component because FControlRigParameter ...

This Blueprint will not compile and causes a crash in 4.8

UE - Simulation - Physics - Mar 18, 2015

The MiningBuilding Blueprint in this user's project will not compile. Clicking the compile button never switches it to "Good to Go", and a warning that it needs to be compiled appears at PIE. Repro ...

A physics actor will still bounce if the Restitution of a Physical Matieral is set to 0

UE - Gameplay - Oct 6, 2016

A physics actor will still bounce if the Restitution of a Physical Matieral is set to 0 User Description: Explanation : I am trying to create a Badminton Game for fun and while I was trying to han ...

DynamicMaterialParameters Niagara module resets write flags on emitter update

UE - Niagara - Feb 4, 2026

When using the DynamicMaterialParameters Niagara module in UE 5.6, 5.7, and UE5-Main (CL 50298778), updating an emitter causes Boolean values, such as Index0Float0Write, to reset to default values, ...

DOF - TAA pass ghosting when using r.DOF.TAA.CoCBilateralFilterStrength

UE - Rendering - Graphics Features - Aug 7, 2025

In Unreal 5.6, there's a new CVar: r.DOF.TAA.CoCBilateralFilterStrength, which should help with ghosting artifacts introduced by TAA in DOF passes. However, it doesn't work as expected since many gh ...

Inconsistent behavior with spawned actors when Play, Pause, and Stop are called in a Level Sequence Player

UE - Anim - Sequencer - Feb 15, 2017

This is a report about three different issues that are tightly related to each other, so I decided to include them in a single report. The behavior of actors spawned by a Level Sequence Player is no ...

Importing through Python fails

UE - Editor - Content Pipeline - Import and Export - Feb 20, 2019

Version 4.21:The script result in popping the Alembic Import windows instead of a silent importThe provided options are ignored by the importer.  Version 4.22: Results in the provided callstack wi ...

Cannot select child anim BPs for use in linked anim layers

UE - Anim - Runtime - Jul 15, 2021

From UDN: [Link Removed] Unable to set a Child ABP with inherited interface to a Linked Animation Layer Instance Class. I have a ABP_Biped which is our main ABP. I have the locomotion (idle+straf ...

Physics Constraint Actor: When plasticity is enabled, Drive Position Target is reset to zero on constraint initialization

UE - Simulation - Core - Mar 5, 2026

When a Chaos joint constraint is first created, having linear/angular plasticity enabled will unexpectedly force its linear/angular drive position target to zero on initialization, disregarding the ...

[CrashReport] UE4Editor_Foliage!operator<<() [foliageinstancebase.cpp:93]

UE - World Creation - Worldbuilding Tools - Foliage - Jul 5, 2016

This Jira was created from CrashReports submitted by the public due to the high number of occurrences. Descriptions from users are provided below. Error message: Fatal error: [Link Removed] [Line: ...