Assertion opening blueprint with HISMC created in 4.11

UE - World Creation - Worldbuilding Tools - Foliage - Jun 7, 2016

After project was upgraded to 4.12 opening a blueprint that contains Hierarchical Instanced Static Mesh component will result in a crash. From the log I this is the important part: Assertion faile ...

TPropertyValueIterator skips TMap values when KeyType is a UStruct

UE - Foundation - Core - May 7, 2018

From https://udn.unrealengine.com/questions/431271/tpropertyvalueiterator-skips-tmap-values-when-keyt.html The property value iterator has logic where it tries to iterate over all properties in a s ...

Sequencer does not save asset variables in event struct

UE - Anim - Sequencer - Jul 31, 2018

When adding a struct to a keyframe, Object Reference variables are not saved and Soft Reference variables are saved sometimes. Opening a keyframe's properties when the selected struct has an object ...

Crash caused by Buffer Overread in TBitArray operator < function

UE - Foundation - Core - Aug 29, 2018

A licensee has reported a crash that is caused by a Buffer Overread in TBitArray's operator < function. While the licensee did not provide reproduction steps, the crash is apparent from looking at t ...

Crash on loading pre-4.20 cloth data when compute skin cache is enabled in 4.21

UE - Graphics Features - Mar 19, 2019

According to information from the licensee, the else clause was added to "FSkeletalMeshLODModel::(GetClothMappingData()" at CL 4437969 , but if it is the cloth data existing from 4.20 or earlier, it ...

Compile on load crashes for classes within an abstract class

UE - Gameplay - Blueprint Compiler - Feb 20, 2021

When compiling on load in -game, a blueprint class that inherits from a native class that is marked within and the class that it is within is abstract, a crash will occur when FBlueprintCompilationM ...

Incorrect volume bounds check in FTranslucentLightInjectionCollector::AddLightForInjection

UE - Graphics Features - Apr 8, 2025

The 'VolumeBounds' array in FTranslucentLightInjectionCollector::AddLightForInjection is accessed as a pointer instead of with 'VolumeCascadeIndex' and thus fails bounds checks for the outer volume. ...

Random Number Generated in Constructor Returning Different Value on Begin Play

UE - Gameplay - Jan 13, 2016

When generating a random number using FMath::RandHelper() in the constructor of an actor, attempting to print that same number on BeginPlay returns a different value than the constructor. However, ...

Hot reloading changes to a struct causes data table assets to break

UE - Gameplay - Mar 28, 2017

If a data table asset is based on a custom struct, making changes to and hot reloading the struct will not update the data table in the editor. Restarting the editor will prevent the data table fro ...

Certain combined Linear/Angular movements cause Client to freeze for several seconds

UE - Simulation - Physics - May 24, 2019

When using Replicated Movement, certain combined linear/angular movements cause the client to freeze for several seconds and then catch up to the server. This is a regression from 4.21.2 (CL-4753647 ...