A partially broken Geometry Collection ends up with garbage CollisionGroup data that can lead to strange behaviors

UE - Simulation - Physics - Destruction - Apr 27, 2025

A partially broken Geometry Collection (GC) ends up with garbage CollisionGroup data that can lead to strange behaviors. The licensee has noticed that a GC that goes thru a field applying ExternalS ...

Crash when exporting static mesh actor to FBX (Array index out of bounds)

UE - Editor - Content Pipeline - FBX - Apr 25, 2025

I set the Forced LOD Model on the mesh component > 1, then tried to export, this is what causes the crash. Here is my suggested fix, we just don't use Git or I'd do a PR: In the else() branch of FF ...

Engine no longer compiles after backporting RHI thread improvements and crash fix

UE - Rendering Architecture - RHI - Apr 24, 2025

Unreal Engine 5.4 code will no longer compile after applying both the RHI improvement code changes as described in [Link Removed] and the fix for the crash described in [Link Removed]. The compilati ...

Launching multiple Editor processes in UE 5.5 can throw warnings due to USD Core plugin initialization

UE - Editor - Content Pipeline - USD - Apr 23, 2025

Launching multiple Editor processes at the same time with the USD Core plugin enabled can cause warnings to be logged like the following:LogUsd: Warning: Failed to update LibraryPath for USD plugInf ...

Divergent group barriers in Lumen

UE - Graphics Features - Lumen - Apr 23, 2025

Intel reported GPU crashes on their hardware caused by divergent group barriers in ScreenProbeConvertToIrradianceCS:[numthreads(THREADGROUP_SIZE, THREADGROUP_SIZE, 1)] void ScreenProbeConvertToIrra ...

GAS: DefaultSubobject AttributeSet becomes invalid on duplicated blueprint

UE - Gameplay - Gameplay Ability System - Apr 22, 2025

When a native actor 'AMyActorClass' creates AttributeSets as a default subobject via CreateDefaultSubobject, duplicating an actor blueprint based on AMyActorClass will result in a blueprint with an ...

[UDN 18615482] SPropertyMenuComponentPicker crashes depending on clipboard contents

UE - Editor - Workflow Systems - Apr 17, 2025

[Link Removed] From UDN: "The component picker has a Paste option and when trying to decide if it should be enabled or not it attempts to load a class using the clipboard contents as a class name. ...

FStateTreeExecutionContext::GetDebugInfoString() outputs wrong info and crashes when using linked state trees

UE - AI - Debugging - Apr 17, 2025

When using State Trees, the AI Debugger can be accessed during play to show information about their current execution state. If a behavior tree is currently in a state that references a linked tree, ...

Change of rotation axis when switching solver

UE - Simulation - Physics - Apr 17, 2025

This alteration was introduced in the 'Found CL' field - and is likely an unintentional side effect of adding SIMD to the solver. There is a repro project attached, open up 'TestMap' and run to see ...