VC Runtime not in UnrealLightmass temp directory; causing lightmass build errors

UE - Foundation - Cpp Tools - UnrealBuildTool - Oct 14, 2015

A Redistribute file for VS 2015 is needed to build lightmass, but this is not currently included with the engine. If a user does not have VS 2015 installed, lightmass will fail with this error: Un ...

Disabled Skeletal Mesh Sections cause Shadow Ray Tracing Flicker

UE - Graphics Features - Dec 12, 2025

If a skeletal mesh has a section disabled the ray traced shadow will flicker when the camera or itself moves. Previously in 5.6.0 no raytraced shadow would appear if a section was disabled. This wa ...

Collision Drawing in Cooked Builds (Development) doesn't Show Geometry for Nanite Meshes

UE - Graphics Features - Jun 2, 2025

Context The showFlag.CollisionVisibility 1 cvar is a viewport visualization mode that highlights which Actors will block visibility. The showFlag.CollisionPawn 1 cvar is a Player Collision viewmode ...

Regression: FAnimInstanceProxy memory leak when BeginDestroy() called on UAnimInstance before USkeletalMeshComponent

UE - Anim - Runtime - Feb 10, 2025

In UE 5.5, the fix applied by CL 36529858 in ue5-main updated USkeletalMeshComponent::ClearAnimScriptInstance() to call AnimScriptInstance::UninitializeAnimation() on the animation instance. This, i ...

Mutable constant texture variable with ClipUV mask only works with new experimental dynamic variable is connected as well

UE - Anim - Mutable - Sep 22, 2025

We are attempting to use Mutable in 5.6.1 and have encountered an issue which we are not sure how to resolve. The issue occurs when using the ClipWithUVMask node. In short we have a customizable o ...

Moving all the related assets to another folder at once leads to reference lost in the contents browser.

UE - Editor - Content Pipeline - Content Browser - Aug 23, 2017

Moving all the related assets into another folder leads to reference lost. This can be tested out using ShooterGame project. Also you can find materials in the skeletal mesh lost its texture. This ...

BuildPatchTool crashes on Mac and Linux when building android or ios with multiple chunks

Portal - Feb 18, 2020

"It seems that deallocation of TLazySingleton<FInternationalization> causes unhandled exception. If DISABLE_LAZY_SINGLETON_DESTRUCTION=1 is provided - the build completes successfully" ...

UMG Editor Will Compile Incorrect Node And Crash When Called During Runtime

UE - Editor - UI Systems - Dec 26, 2019

The UMG editor will compile as if the blueprints is valid if you make "Get Text" node from a TextBlock variable, delete it and create a EditableText variable with the same name. When running a scene ...

Mutable references MetaHumans heads directly, but DNA Assets are private

UE - Anim - Mutable - Sep 18, 2025

When we switched our project to 5.6.1 This error appeared on build. The compilation of the Mutable assets in the editor is not reporting any issue. ...

Changing the name of a GameMode Blueprint that is set as the Default in Project Settings and then clicking the Project Settings Default GameMode dropdown will crash the editor

Tools - Jul 7, 2015

Changing the name of a GameMode Blueprint that is set as the Default in Project Settings and then clicking the Project Settings Default GameMode dropdown will crash the editor. No crash report is ge ...