Editor 'Build All Levels' discards Volumetrics Lightmaps in persistent level

UE - Graphics Features - May 14, 2025

Building the level or lightmaps can clear the volumetric lightmap. In 5.5, this requires you to perform a full build, or a lighting only build with a BSP brush in the scene. In 5.6, all level build ...

Ensure triggered with multiple AddInstance() calls for InstancedStaticMeshComponent

UE - Graphics Features - May 20, 2016

Adding multiple instances to instance static mesh component in a code class causes an ensure to trigger when an instance of the class is added to the level. ...

Cannot compile nativized Blueprints containing a delegate signature that includes a TMap (paired) type as a parameter.

UE - Gameplay - Blueprint - May 15, 2018

Paired types (e.g. TMap) in a delegate signature do not compile after nativizing a Blueprint class containing it due to the macro expansion and comma inside the template spec between key and value t ...

Mobile Previewer: Safe Zone Invalid Until Window Resize

UE - Platform - Mobile - Jul 12, 2021

When 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. ...

[CrashReport] UEdGraphSchema_K2::PinHasSplittableStructType

UE - Gameplay - Blueprint - Sep 14, 2017

This crash is affecting a few users in 4.17. ...

IOS crash disabling idle timer when closing the app

UE - Platform - Mobile - Apr 29, 2020

Licensee report of crash during shutdown due to setting [UIApplication sharedApplication].idleTimerDisabledbeing from the Game thread. Grouped together with others items in [Link Removed] ...

A Blueprint containing an array Swap node will fail to be nativized.

UE - Gameplay - Blueprint - Jul 17, 2020

Blueprint assets that utilize an array "swap" node to swap elements cannot currently be converted to C++. Current workaround: Either avoid use of the "swap" node or exclude the Blueprint asset from ...

Custom UVs don't store information properly in layered materials.

UE - Rendering Architecture - Materials - May 9, 2022

[Link Removed] I have this set up so that FX artists can stack UV manipulations, so I don't want to just have all the UV manipulation in the layer with the base color, even though that does give me ...

[CrashReport] Fatal error: Cast of nullptr to Actor failed - UE4Editor_CoreUObject!CastLogError()

Tools - Jul 19, 2017

This is a common crash affecting users in 4.16, and has been occurring since at least 4.14. It has affected more than 400 unique users, unfortunately they have provided little information. User Des ...

UE4Editor crashes while closing on Ubuntu 14.04

UE - Platform - Linux - Mar 29, 2017

UE4Editor crashes when closing on the Ubuntu 14.04 machine. I do not see this issue on my Ubuntu 16.04 machine. ...