"Combine Meshes" Breaks Material Slot Assignment

Tools - Jan 18, 2017

When importing an FBX with several different meshes and multiple materials with "Combine Meshes" enabled the materials will get assigned to incorrect portions of the mesh. I've included a version o ...

Actor instance FComponentReference to other actor instance gets nulled on other actor recompile

UE - Gameplay - Blueprint Compiler - May 21, 2024

An editable FComponentReference property on an actor instance can be used to reference another actor's component in the scene. In 4.27 and earlier versions these references were retained when the ot ...

Crash after network disconnection/pulling network cable

UE - Networking - Jul 11, 2019

A very unfortunate bug shipped in 4.22 that causes a crash in many cases when a client is disconnected from the network, such as when unplugging the network cable. This will be a cert failure on con ...

Landscape Layer Blend generates bad code for preview shader

UE - LD & Modeling - Terrain - Landscape - Sep 23, 2019

It breaks only when compiling the preview shader. Adding a preview weight to the Layer0 on the Layer Blend node fixes the problem. The source of the bug is in UMaterialExpressionLandscapeLayerBlend ...

Cash when entering Path Tracing view mode if r.Decal.NormalReprojectionEnabled true

UE - Graphics Features - Path Tracer - May 16, 2025

Cash when entering Path Tracing view mode if r.Decal.NormalReprojectionEnabled true The licensee has reported: This crash happens because the DeferredShadingRenderer tries to extract the normal GBu ...

DataTable::LoadStructData allocating wrong size

UE - Foundation - Core - Oct 5, 2016

Pointed out by a licensee here: UDataTableを読みこんだ際のメモリ破壊について When reading the `UDataTable, in DataTable::LoadStructData()` the contents of the struct are interpreted[Image Removed], but the size of ...

UDN : Mutable Trying to Access Invalid UEdGraph Pointer

UE - Anim - Mutable - Mar 6, 2025

Hello, We've started seeing a crash within Mutable when it tries to access the source graph in PIE. This only seems to be a problem when running a dedicated server as a separate process. We integra ...

Crash when travelling during ability activation when URL contains "#"

UE - Framework - Jul 18, 2025

This issue is related to [Link Removed], where the "?listen" option sent on the URL to clients could cause issues with RPCs being called locally during travel. The fix to remove the "?listen" option ...

Fbx importer can import valid under 30Hz anim at 30Hz

Tools - Jul 17, 2017

The samplerate of a track was compute with the following formula Equation 1: number of Key / animation Time This formula work only if we have animation keys that are time equidistant. example of ...

Surface Profile Skin shading has some unexpected stripe rendering issues

UE - Graphics Features - Apr 3, 2018

So it looks like the artifact is definitely related to whether sss checkboard is enabled, but I can't reproduce it if enabling checkboard right after open the map, I mean it has to be reproduced aft ...