Adding a widget to a grid panel inside the grid panel tick can cause an out-of-bounds error

UE - Editor - UI Systems - Slate - Jan 25, 2021

This is caused by adding an item to a grid panel inside the grid panel iteration loop. The same operation to canvas panel goes well without any errors. The difference is that the array iteration in ...

Crashes when copying an array of actors that implement an interface into an array of interface references

UE - Gameplay - Sep 17, 2019

When assigning an array of actors that implement a specific interface to an array of the specific interface the engine crashes. This doesn't happen if the actor array is put through a for each loop ...

Cached component instance data transform did not match! Warnings in Content Examples

Docs - Samples - Oct 27, 2016

Lighting is unbuilt in all levels in Content Examples. Multiple warnings appear in the log "Discarding cached lighting data which will cause lighting to be unbuilt" LogStaticMesh:Warning: Cached co ...

Particles Do Not Obey Lighting Channels

UE - Niagara - Apr 17, 2018

Particle systems ignore lighting channels - no matter what channel a light is on (even if no channels are selected), it will affect lit particles. Changing lighting channels on the particle itself h ...

Material Parameter Collections are not working on Android v 5 phones from 4.11

UE - Platform - Mobile - Feb 9, 2016

Material Parameter Collections are not successfully passing stored values into Materials when packaged for an Android Phone with an OS version of 5. Both version 4 and 6, correctly use the MPC.Test ...

HideBoneByName translates bone to parent which breaks skinning

UE - Anim - Jul 30, 2024

Calling HideBoneByName on a bone causes that bone (and all it's children) to be translated to the parent bone's location.  This code in UpdateRefToLocalMatricesInner is responsible: bool bNeedToHid ...

Crash occurs loading a sublevel containing landscape with ray tracing enabled

UE - LD & Modeling - Terrain - Landscape - May 13, 2020

In raytracing enabled, When loading a sublevel containing landscape with LoadStreamLevel function following error is shown. Assertion failed: Pair != nullptr [Link Removed] [Line: 584] Licensee re ...

GPU-ARM Mali 400 series phones will render an Opaque Unlit Material as black

UE - Platform - Mobile - Feb 12, 2016

ARM Mali 400 Series GPUs are rendering Opaque Unlit Materials as Black instead of the designated color. This is a *regression* from 4.10.2.Devices where Issue OccursDevice NameBrandBug Description ...

TMap<Bool is disallowed despite bool having a hash

UE - Gameplay - Blueprint - Nov 22, 2022

Reproduced 3/3 times. User is unable to create a new TMap with bool key through Blueprints (which is the expected result).  Issue is technically a Regression, as the ensure does not occur in //UE5/ ...

FileSystemDerivedDataBackend may output a corrupted access log

UE - Foundation - Core - Derived Data - May 20, 2021

This problem is caused by the AccessLogWriter has not been flushed at the termination. The following workaround flushes the Writer.class FFileSystemDerivedDataBackend : public FDerivedDataBackendInt ...