FVector::Normalize does not set Vector to (0,0,0) upon failure, as described

UE - Foundation - Core - May 24, 2017

The FVector::Normalize function states in its comment that if given a vector that is too small to be normalized, it will set it to 0,0,0 and return false. The function only returns false and does no ...

Regression: Asset Action Utility "Supported Classes" setting is not working correctly when "IsActionForBlueprints" is true

UE - Editor - Workflow Systems - Aug 16, 2024

When creating an Editor Utility Blueprint derived from "Asset Action Utility", UE allows the user to override function "IsActionForBlueprints". When it returns true, the "Supported Classes" setting ...

UMG widget callbacks do not set PIE context in editor

UE - Editor - UI Systems - May 21, 2018

This is from a UDN post. Several gameplay functions, such as level streaming and SoftObjectPtr resolution, depend on the GPlayInEditorID being set when that code is executed in PIE in the editor. T ...

"DefaultToSelf" pin ignores parameter type

UE - Gameplay - Blueprint - Mar 5, 2015

A user reported an issue resulting in a crash with callstack pasted below. After a brief investigation I've found that user was able to successfully compile a blueprint where a function taking an ...

Crashes after destroying a skeletal mesh attached via socket name (not bone name), the destroyed mesh remains welded.

UE - Simulation - Physics - Jul 18, 2025

On welding physics bodies during primitive component attachment, UPrimitiveComponent::WeldToImplementation() calls GetRootWelded() and then GetBodyInstance() on the returned root. This searches by b ...

Static meshes with auto-generated LODs can no longer share lightmaps between LODs

UE - Graphics Features - Feb 21, 2017

User report: With 4.15 using only auto generated LOD's static mesh LOD levels can't share computed lightmaps anymore. This cause severe memory increase and it's making lightmass build times way slow ...

Two Incompatible Object types are able to connect via add array in Blueprint Graph.

UE - Gameplay - May 21, 2019

it is possible to connect two incompatible types to an Array Blueprint function node by connecting the Item pin first.  The type of Array function nodes is determined by the first thing connected t ...

USplineMeshComponent::CalcBounds may return invalid value

USplineMeshComponent::CalcBounds function should be returning an FBoxSphereBounds type, but in the implementation it instead outputs an FBox. This may result in the returning of invalid results, esp ...

FNiagaraStackGraphUtilities::FindScriptModulesInStack() parameter "OutFunctionCalls" should be a reference

UE - Niagara - Aug 11, 2025

On file [Engine\Plugins\FX\Niagara\Source\NiagaraEditor\Public\ViewModels\Stack\NiagaraStackGraphUtilities.h], function FNiagaraStackGraphUtilities::FindScriptModulesInStack() receives a parameter " ...

Multithreading Race Condition Crash with Anim Montages

OLD - Anim - Apr 2, 2015

Basically, the problem is that the Main Thread is able to run AActor::Tick() (including Blueprint Tick Events) at the same time that the animation system is running functions such as UAnimInstance:: ...