The OnUnPossess() method of the AAIController class is triggered twice

UE - AI - Apr 21, 2020

The OnUnPossess() method of the AAIController class is triggered twice ...

EnumRedirections from a Blueprint enum to a c++ enum does not redirect everything correctly.

UE - CoreTech - Aug 20, 2024

There is an engine bug when using the EnumRedirects feature inside a config file. If we have a Blueprint Enum used in our blueprints, and we want to convert all the Blueprint enum references to a C+ ...

Hardware Lumen Surface Cache Artifacts on Nanite Geometry

UE - Graphics Features - Lumen - Sep 1, 2025

When using Hardware Lumen with Nanite-enabled meshes in UE 5.6+, black / dark surface cache artifacts appear that result in generally darker and unstable lighting. These artifacts are not immediatel ...

Chaos sometimes can not generate contact points while two dynamic convex hulls actually collide. It results in instability in the contact behavior​ - such as jittering, inconsistent contact forces, or unexpected collision responses.

UE - Simulation - Core - Dec 2, 2025

Context: Chaos Physics is able to use convex hulls to represent object collision geometry for queries and simulation. Problem: Chaos sometimes can not generate contact points while two dynamic conv ...

Cloth jitters in Movie Render Queue renders when temporal sampling is enabled

UE - Anim - Sequencer - MRQ - Dec 6, 2022

The Cloth simulation time step smoothing is interfering with the substepping fix for multi Temporal Samples by changing the very variable DeltaTime and causing some large errors in the cloth simulat ...

Crash when a Deferred Decal (Translucent) base material has a Nanite Override (Masked Surface) Material and the mesh has Nanite + Ray Tracing enabled.

UE - Graphics Features - Ray Tracing - Aug 14, 2025

A crash occurs when Nanite override material instance is used in a project with Ray tracing enabled where: 1 The Material assigned to the static mesh uses Deferred Decal / Translucent and the Nani ...

[HORDE] Workspace does not respect stream view if the paths within the stream change to a newer CL then that of the stream

UE - Foundation - Horde - Dec 9, 2025

For example, if you have the engine in a different stream and specify an exact CL to use on the import path, you then update that import path to a later change with a higher CL number than that of t ...

Gameplay effect modifier tag requirements are not checked for Instant/periodic effects

UE - Gameplay - Gameplay Ability System - Jun 19, 2023

When creating a GameplayEffect, modifiers can tag requirements for the Source and Target tags. For Duration gameplay effects, these tag requirements are checked from FAggregatorMod::UpdateQualifies ...

Bluerpint nativization failed for calling TMap::Find function of a map container with an enum type key

UE - Gameplay - Blueprint - Oct 2, 2020

Followings are nodes in the repro project. [Image Removed] Here's a generated code of the BPvoid ANewBlueprint_C__pf1010915279::bpf__NewFunction_0__pf() { uint8 bpfv__CallFunc_GetInt_NewParam ...

Crash when loading array of UStructs containing Instanced property

UE - Gameplay - Blueprint - Jan 26, 2022

The editor crashes with a failed assertion when opening a blueprint actor that contains a structure with instanced objects. ...