StructUtils plugin's `FInstancedStruct` in a CPP-defined struct in a `TArray` on an actor component defined in CPP and implemented in BP. Populating the instanced struct in an actor BP's class defaults breaks serialization of the class defaults.

UE - AI - May 30, 2025

Context Instanced structs are great for holding simple data with the main advantage they have is a low memory overhead unlike instanced objects. Problem The problem is in StructUtils plugin's `FIns ...

Meshes with no UV Coordinates will break the UVs of other meshes contained in the same HLOD if they share a material

UE - World Creation - Worldbuilding Tools - HLOD - Aug 26, 2016

Meshes with no UV Coordinates will break the UVs of other meshes contained in the same HLOD if they share a material this only occurs depending on the specific order ...

Character sliding down a surface can prematurely land before reaching a walkable floor

UE - Gameplay - Player Movement - Apr 3, 2024

Under some circumstances, a character falling and sliding along a sloped surface may get hung up near the bottom of the surface before actually landing on the floor.  This seems to occur when slidin ...

Add Actor World Offset does not work consistently with physics-enabled objects

UE - Simulation - Physics - May 3, 2022

Add Actor World Offset does not work consistently with physics-enabled objects Repro Rate: 3/3 Tested this in //UE4/Release-4.27 @ CL#18319896 and the issue did not occur there, it is a regression ...

Make Bitmask node returns incorrect value when using custom Enum

UE - Gameplay - Blueprint - Jul 5, 2016

When a custom enum is used as the Bitmask Enum of a Make Bitmask node, the value returned does not match the expected value ...

[CrashReport] UE4Editor-CoreUObject!FPropertyProxyArchive::operator<<(FField * &) [PropertyProxyArchive.h:45]

UE - Foundation - Cpp Tools - Hot Reload - May 8, 2020

Generated from CrashReporter Error message - Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address [different address per crash] ...

Nanite can assert in ValidateFixupChunk: 'Assertion failed: HierarchyNodeIndex < Resources.NumHierarchyNodes'

UE - Graphics Features - Nanite - Aug 29, 2024

Reported by a licensee. More discussion in the linked UDN case. "Sometimes the WorldPartitionBuilderCommandlet will fail after encountering this error:" Error: Assertion failed: HierarchyNodeIndex ...

Crash When Attempting To Change LOD1 Cloth Assigned

UE - Simulation - Physics - Character - Apr 12, 2017

At times when trying to assign APEX cloth to LOD1 material the engine will crash. I got a 100% repro rate following the steps listed above. I have found some inconsistent errors when trying to rep ...

AbilitySystemComponent::NotifyAbilityEnded Can Crash due to Callbacks Invalidation Specs

UE - Gameplay - Gameplay Ability System - Oct 11, 2023

Pasting from the UDN: Unsafe code in AbilitySystem can lead to crash when granting an ability inside OnAbilityEnded Hello. We just ran into a crash. After investigation, it seems to be caused by ...

FIOSInputInterface::SendControllerEvents crash due to UIInterfaceOrientation call from game thread

UE - Platform - Mobile - Apr 29, 2020

From [Link Removed], licensee reports We believe that querying the UIInterfaceOrientation via UIApplication on the game thread is the issue here. We have made changes to IOSInputInterface.cpp and I ...