Compilation error when using Particle SubUV in Niagara Mesh Particles with Raytracing enabled.

UE - Niagara - Oct 12, 2021

The licensee has shared the following workaround for modifying NiagaraMeshVertexFactory.ush. struct FVertexFactoryInterpolantsVSToPS { TANGENTTOWORLD_INTERPOLATOR_BLOCK #if USE_PARTICLE_SUBU ...

FStateTreeExecutionContext::GetDebugInfoString() outputs wrong info and crashes when using linked state trees

UE - AI - Debugging - Apr 17, 2025

When using State Trees, the AI Debugger can be accessed during play to show information about their current execution state. If a behavior tree is currently in a state that references a linked tree, ...

Failed to build in Github UE4.27.0.

UE - Simulation - Physics - Aug 30, 2021

Failed to build UE4.27.0 with Win64/Development Editor.  Can avoid this error that excluding the project from build configuration. (Solution UE4->Properties->Configuration Properties->Configuratio ...

Linked Anim Graph in Post Process Anim BP does NOT work after remove ControlRig Track

UE - Anim - Rigging - Control Rig - Oct 11, 2022

After remove control rig track from the skeletal mesh, Linked Anim Graph in Post Process Anim BP of the SK Mesh does NOT work. This issue can be fixed by the following code.// add #include "Anima ...

When PCH is Disabled, Error Occurs in VulkanGenericPlatform.h at Android Build

UE - Graphics Features - Dec 6, 2018

If disable PCH in Target.cs, an error will occur when building for Android. The log is as follows. LogPlayLevel: Error: D:/Build/Release-4_21_0/Engine/Source/Runtime/VulkanRHI/Private/Android/../Vu ...

Vive Trackpad X and Y always return 0

UE - Platform - XR - Feb 3, 2020

Platform-specific input for pad axis in 4.24 leads to missing value in VIVE. in 4.23.1 this is not reproduced. ...

Blueprint processing is heavy in PIE since 4.26

UE - Gameplay - Blueprint - Feb 17, 2021

As the attached image shows, there is no problem in 4.25.4, and the process is noticeably slower in 4.26.1. Also, there is no problem in Standalone. The problem occurs only in PIE. ...

Volumetric Clouds High Quality Aerial Perspective Issue

UE - Rendering Architecture - Oct 19, 2023

There is a workaround to set r.VolumetricRenderTarget.Mode=1. The lines appear to be coming from the temporal component of the Volumetric Clouds. Each frame, the lines are merged in from the previou ...

Blueprint Launches onto tvOS fail during runstep: Error_DeviceOSNewerThanSDK

UE - Platform - Mobile - Apr 19, 2019

When a user launches blueprint project to a tvOS device they will fail to run the project during the run step and if they manually try to launch the app from the dashboard. This issue does not repr ...

Assets on paths with speed parameters are sped up in Path Tracer exports

TM - Rendering - Jul 18, 2025

Reported in SF [Link Removed] In Path Tracer renders, all paths with a speed component (vehicles, bicycles, custom) will render at an increased speed than specified in the exported render. This is ...