Fix iterative cooks to keep track of CookAdditionalFiles and delete them when the package file that created them is invalidated

UE - Foundation - Data Pipeline - Cooker - Sep 23, 2022

A licensee reports they are using the CookAdditionalFilesOverride function in UObject to add files to the project. This file is properly copied into the Staging area during Packaging, and is appropr ...

Bug in StringTemplate.cpp related to modulo operator in MaterialTemplate.ush (code fix provided)

UE - Rendering Architecture - Materials - Jun 25, 2024

Shader Template files like MaterialTemplate.ush do not submit previous chunks when encountering a `%` character, unless that `%` character is `%s` or `% {...} `. Because the error is happening ...

Make Custom Event names start with "Event"/Fix "Event Event" issue with overridden Events

UE - Gameplay - Blueprint - Dec 17, 2015

If you name an Event something like "Event Foo", overriding the event in a ChildBP gives you "Event Event Foo" To avoid this, please make Custom Event names Start with "Event" ...

Crash on Adding Elements to Array On Instance of Actor in the Level

Tools - May 25, 2018

When attempting to add an array element to an array that exists on a component contained within an actor that is instanced in the level, the editor will crash. This does not occur if an array elemen ...

Previewing Node in Material Editor Produces Unexpected Output with DX12

UE - Graphics Features - May 16, 2018

Per Licensee: Since we switched to DX12 we started to see strange behavior in material previews. I was able to reproduce the problem in UE 4.19 vanilla as well. We usually have to force recompilin ...

Crash when using StaticDuplicateObject with mismathced Source and Destination class types

UE - Foundation - Jun 19, 2025

Starting in Unreal Engine 5.4, StaticDuplicateObject internally switched to using Unversioned Property Serialization (UPS) for performance reasons. However, UPS assumes the source and destination ob ...

Opening Materials and Material Functions with Vertex Interpolator node Results in Crash

UE - Graphics Features - May 23, 2018

Per Licensee: Hello, We are migrating our project from 4.18 to 4.19.2 and we are encountering various crashes while opening our material and material functions. I'm adding a simple test case here. ...