[CrashReport] Assertion on in UMaterialInterface::InitDefaultMaterials()

UE - Graphics Features - Jun 28, 2017

This is a common Mac crash occurring in the 4.16.1 release. I have not found any evidence of it occurring on Windows. The callstack closely matches [Link Removed], which was briefly experienced by ...

UAssetManager::ChangeBundleStateForPrimaryAssets: Performance: Avoid canceling loads in progress when new bundles added and the in progress bundles are kept

UE - Foundation - Data Pipeline - Cooker - Mar 4, 2024

UAssetManager::ChangeBundleStateForPrimaryAssets allows adding new BundleNames to the list of BundleNames loaded for a PrimaryAssetId. Each BundleName specifies a BundleEntry with a list of assets. ...

Sequencer - When a subsection has negative play rate, any nested sub-subsections fail to evaluate

UE - Anim - Sequencer - Jul 3, 2025

Consider a sequence hierarchy with more than two layers. If the top-level sequence uses a negative timescale on a sub-sequence, the contents inside it animate as expected, but any nested sub-sequenc ...

Crash when a subsystem calls GetSubsystemArray() on its owner while engine code is iterating on subsystems also obtained through GetSubsystemArray()

UE - Gameplay - Aug 6, 2024

In some occasions, engine code iterates over a certain subsystem type by calling FSubsystemCollection::GetSubsystemArray() and then calling some method on all subsystems of the returned array. This ...

Unknown force is applied to the cloth when changing the skeletal mesh LoD with cloth.

UE - Simulation - Physics - Character - Jul 11, 2019

There are 3 issuesEach particles don't restore its previous position. Which is for calculating velocity by verlet iteration.The previous transform is cleared by current transform. It provides zero v ...

Constraint axes are not visible in Physics Asset editor viewport

OLD - Anim - Jul 10, 2017

This is a regression from 4.16 as I was not able to repro this issue in //UE4/Release-4.16 at CL 3514769. ...

MovieRender Pipeline Skips Output Frames during GC

UE - Anim - Sequencer - Jun 8, 2020

This is being seen in the wild... can release a temporary fix until 4.26 when we can change the headers and fix it for real. ...

Transform key don't visible when Import From Animation Root

UE - Anim - Sequencer - Mar 7, 2018

Transform key don't visible when Import From Animation Root. This problem happen from 4.17. 4.16 is visible. Case:4.16[Link Removed] ...

Reintroduce UE4 Material Layer drag & drop behavior in UE5

UE - Rendering Architecture - Materials - Oct 19, 2023

This behavior has changed from UE4 to UE5 due to a fix to an unrelated bug ([Link Removed]). Reintroduce the old behavior without causing a regression that reintroduces Ben's fixed bug. ...

COTF has issues with out-of-source projects

It is expected that cooking, including COTF, will fix-up all string asset references. There were a few reasons this wasn't happening, but we should get these fixes into 4.15 as the impact was worst ...