If a custom code class is modified and a Hot Reload performed, any existing unsaved Blueprints derived from that class can no longer be saved.

UE - Gameplay - Blueprint - Feb 19, 2015

When a custom code class is changed and a Hot Reload is performed, any Blueprints previously made from that class can no longer be saved. Possibly related to [Link Removed]. WORKAROUND: Close and ...

Client PlayerState is null on joining online session

UE - Networking - Jul 31, 2015

APlayerController::ClientStartOnlineSession() checks PlayerState at the start of a game after loading a level. Due to time needed to load in, client player state may may return NULL ...

Hierarchical LODs used with Precomputed Visibility cause actors to occlude that should not behind translucent materials

UE - Graphics Features - Jul 6, 2016

When using Precomputed Visibility in conjunction with HLODs and translucent materials without them culling actors occluded by the translucent material. The example gif attached shows that the base ...

[CrashReport] UE4Editor_ShaderCore!FShader::GetVertexShader() [shader.h:568]

UE - Graphics Features - Nov 21, 2017

This is a common and longstanding crash that has occurred since at least 4.16 User DescriptionsTrying to paint my new sandtexture onto the terrainOpened the material editor by double clicking a mat ...

FBlackboardKeySelector filters aren't applied when recompiling blueprint if a behavior tree asset containing the blueprint added as a service is closed, or if the blueprint is reparented.

UE - AI - BehaviorTree - Sep 24, 2025

Context In Behavior Trees, BT Services can be added to nodes. Those services can have configurable FBlackboardKeySelectors. BlackboardKeys are variables on a blackboard that the behavior tree can r ...

Children of editor-only actors do not maintain correct transforms when placed inside level instances for PIE and cooked builds

UE - World Creation - Worldbuilding Tools - Level Instances - Oct 20, 2025

We have found an issue where children of editor-only actors get wrong transforms in PIE and cooked builds when placed inside level instances. This affects both engine version 5.5 and 5.6. The issue ...

Renaming a Blackboard Key removes it's references in the Behavior Tree

UE - AI - Jan 27, 2015

Renaming a Blackboard Key removes it's references in the Behavior Tree ...

[CrashReport] UE4Editor_Renderer!FMaterialShader::SetParametersInner<FRHIVertexShader * __ptr64>() [shaderbaseclasses.cpp:181]

UE - Graphics Features - Jun 19, 2018

No user comments in crash group 172 const bool bOverrideSelection = 173 GIsEditor && 174 !View.Family->EngineShowFlags.Selection && 175 (MaterialRenderProxy- ...

Collision of child actor doesn't rotate if the parent is simulating physics

UE - Simulation - Physics - Aug 11, 2015

Collision of child actor doesn't rotate if the parent is simulating physics. This was an old bug that an AnswerHub user reported back in 4.9 but now a licensee is reporting this same behavior in 4.1 ...

Hidden enumerator variables can cause the enumerator to become broken with the Select node in blueprints

UE - Gameplay - Blueprint - May 26, 2015

If a user makes an enumerator in C++ and sets one of the variables to Hidden and doesn't make it the last variable of the enum, it will cause issues with the numbering of the enum when using the Sel ...