Calling UBlueprintMapLibrary::GenericMap_Find with a non-existent key causes a memory leak

UE - Framework - Blueprint - Apr 15, 2025

When Calling UBlueprintMapLibrary::GenericMap_Find with a non-existent key, the function construct the default structure in-place on the given pointer without destroying the object. This behavior ca ...

Integer Blueprint variables reset the Bitmask Enum setting when the Editor closes

UE - Framework - Blueprint - Feb 28, 2019

User created Bitmask flag Enumerators are not correctly stored and retrieved from Blueprint Integer variable settings. When the Editor is restarted the value of the Integer's Bitmask Enum is set to ...

Attempting to Open a Widget Blueprint With Animation and Timeline Panels Hidden Causes the Editor to Crash

UE - Editor - UI Systems - Nov 11, 2015

When you attempt to open a widget blueprint when you have hidden the animation and timeline panels, the editor will crash. There is a workaround: Window->Reset Layout will allow you to open the blu ...

Cannot change Collision Responses once component is custom selected from scene

UE - Gameplay - Dec 27, 2016

Cannot change Collision Response channel once component is custom selected from scene. This is only an issue if the component is selected by first selecting the actor in the world (scene), then sele ...

Hot Reload fails if a project and Engine are placed next to each other in the same root folder that has the same name as the project

UE - Foundation - Cpp Tools - Hot Reload - Jan 8, 2019

Hot Reload does not work if a project and the Engine that project is associated with are placed next to each other in the same root folder that shares the same name as the project. During the Hot Re ...

[AI] Debug Render Scene Proxy hits ensure for registering a delegate twice during level streaming.

UE - AI - Debugging - Aug 31, 2022

Description from licensee: We're seeing an ensure get tripped up in FDebugRenderSceneProxy that says "DrawDelegate is already Registered!". Debugging the issue, we have confirmed that the DrawDeleg ...

When using 'r.VT.SplitPhysicalPoolSize 64' with nanite meshes, mesh painting does not update in real time (only updates after stroke finished), duplicates mesh painting across separate instances of a mesh, and sometimes doesn't show up in PIE.

UE - Rendering Architecture - Mar 3, 2025

When using Mesh Painting on nanite meshes in 5.5 with 'r.VT.SplitPhysicalPoolSize' set to non-zero values (e.g. 16, 64), several issues occur, such as: 1. Painting doesn't update in real time (only ...

Destructibles using Form Extended structures with rigid body collision gives wrong hit result

UE - Simulation - Physics - Destruction - Jan 7, 2015

DESCRIPTION: When using form extended structure with DMs that are hit by a rigid body the resulting hit does not reflect the correct actor if they are both using form extended. If a DM without form ...

Chaos : Rigid body sleeps when very small external force is applied by AddForce

UE - Simulation - Physics - Solver - May 25, 2022

When a small external force is applied to the rigid body, the VSmooth value is reset in the ResetVSmoothFromForces function. Since this function ignores the current velocity, a very small velocity ...

Attempting to use the GameplayTags module in a binary code project will result in build failures in Visual Studio.

UE - Foundation - Core - Mar 27, 2015

Using the GameplayTags module in a code project created with the binary version of the Engine results in a build failure in Visual Studio. The following error is shown: 1> D:/Epic Games/4.7/Engine ...