Ensure triggered in FBoundsCacheElement::GetValue when adding ISM instances in Construction Script

UE - AI - Oct 8, 2025

An ensure is triggered in FBoundsCacheElement::GetValue when adding instances to an InstancedStaticMeshComponent inside a Blueprint’s Construction Script. This occurs when the ISM component is navig ...

Update prepackaged dotnet to latest 10 patch release due to crash on Mac OS.

UE - Platform - Mac - Sep 24, 2026

A dotnet crash occurs sporadically with a sigsev or sigbus when running on Mac OS. This is in the dotnet executable itself, and can happen on commands like `dotnet build`, not just on executing the ...

Adding an output to the default function of a Blueprint Interface now requires the Interface to be compiled in order to change the output's values

UE - Framework - Blueprint - Mar 15, 2022

In 4.27 immediately upon adding an output to the default function that output can be edited without needing to be compiled. In Preview 2 once an output is added the Blueprint Interface needs to be c ...

[CrashReport] UE4Editor_BlueprintGraph!BlueprintActionFilterImpl::IsEventUnimplementable() [blueprintactionfilter.cpp:588]

UE - Gameplay - Blueprint - Jun 1, 2016

This crash has been reported through the 4.12 Previews and is continuing to occur in the 4.12.0 release. Additional information about this crash is not available at this time, however it may be the ...

ModularGameplay and other runtime plugins have wrong LoadingPhase

UE - Gameplay - Jun 30, 2022

Plugins that provide blueprint-accessible libraries generally need to be set the PreDefault LoadingPhase so they can be properly loaded before game-specific data that loads early in the Default load ...

UV Flipping Mode Causes Stretching of Particles

UE - Niagara - Nov 17, 2017

If "UVFlipping Mode" under Rendering on the Required node of an emitter is set to anything other than "None," the particles can become stretched and distorted. As a workaround, I have discovered th ...

Crash When Assigning a Static Mesh to the "Sample Static Mesh" Module

UE - Niagara - Jun 28, 2018

When assigning a static mesh to the "Sample Static Mesh" module, the engine will crash as soon as you select a mesh and click "Fix Now". If the mesh already has CPU access enabled it will crash as s ...

Edits of node properties that are not stored on pins do not diff correctly

UE - Gameplay - Blueprint Editor - Oct 2, 2015

Currently details changes to the following are not noticed by the Diff tool when diffing AnimBPs:State Machines (i.e. Max transitions per frame)Transition rulesConduitsStates This also affects non- ...

"Combine Meshes" Breaks Material Slot Assignment

Tools - Jan 18, 2017

When importing an FBX with several different meshes and multiple materials with "Combine Meshes" enabled the materials will get assigned to incorrect portions of the mesh. I've included a version o ...

Actor instance FComponentReference to other actor instance gets nulled on other actor recompile

UE - Framework - Blueprint Compiler - May 21, 2024

An editable FComponentReference property on an actor instance can be used to reference another actor's component in the scene. In 4.27 and earlier versions these references were retained when the ot ...