Classes in TargetDenyList modules are still referenced from Components on BlueprintGeneratedClasses and cause runtime warnings

UE - Foundation - Feb 25, 2024

Other than the presence of the error and the performance cost of looking for a package on disk that does not exist, there are no behavioral problems. When running with legacy (non-iostore) pakfiles ...

Niagara Scalability Crash When Processing Significance

UE - Niagara - Jun 4, 2025

Method FNiagaraScalabilityManager::ProcessSignificance() iterates on indices from Context.SignificanceIndices and uses them to access the State and ManagedComponents arrays. It can then decide to cr ...

Mesh Vertex Painting Broken for Splines

UE - Rendering Architecture - May 22, 2023

The mesh painting mode appears to no longer work on splines, as the vertexes seem to have all vertex colors at 1, 1, 1, 1 by default, and can't be removed or painted anything else. ...

DestructibleMesh does not correctly effect vertex color of material.

UE - Simulation - Physics - Destruction - Oct 10, 2017

Destructible Mesh does not correctly affect vertex color. ...

Crash launch application adding .umap url

UE - Foundation - Core - Aug 6, 2020

The application crashes when adding ".umap" to the launch map at application launch. If not specify ".umap", it will be able to launch application. There appears to be a failure to parse the URL. Th ...

FLinearColor ignores Blue in slate code

UE - Editor - UI Systems - Slate - Jan 17, 2017

When FLinearColor is used inside slate code, the third vector value is ignored. This causes FLinearColor(1,1,1) to produce the same color as FLinearColor(1,1,0). This also causes FLinearColor::Blu ...

When ParallelExecutor is enabled, Japanese build output of VisualStudio garbled

UE - Foundation - Cpp Tools - Sep 19, 2018

From UE4.20, Japanese build output of VisualStudio garbled. Below is a comparison between 4.19 and 4.20. ・4.19.2 1>------ すべてのリビルド開始: プロジェクト:MyProject3, 構成:Development_Editor x64 ------ 1> Clea ...

Error launching onto HTML5: "Expression (0) failed in \Engine\Source\Runtime\Core\Private\Async\TaskGraph.cpp:428!"

UE - Platform - Mobile - May 9, 2017

This is launching on to Firefox 53.0.2 (64-bit) and also occurs in Main. Error message:uncaught exception: ASM_CONSTS<@blob:http://localhost:53501/4354ee7b-de4a-419b-b0bc-5d58ff557ed2:1:38655 _emsc ...

Projects crash when launching onto Firefox 64-bit

UE - Platform - Mobile - May 8, 2017

QAGame crashes when it launched onto Firefox. The following exception occurs with the error message:*Expression (0) failed in D:\UE4_Dev-Rendering\Engine\Source\Runtime\Core\Private\Async\TaskGraph ...

When adding the UIRenderer to the Movie Render Queue, the rendering output is a difference in PIE and MRQ.

UE - Anim - Sequencer - MRQ - Dec 5, 2023

UI rendering in PIE and UIrenderer rendering in MRQ produce different output results. This is because when dealing with fades in the UI, the rendering results should not be different.  Workaround ...