Delta struct serialized fast arrays replicating new elements with no changelist

UE - Networking - Jun 14, 2021

There is a scenario where delta struct serialized fast arrays can replicate changes that introduce additional elements to the array, but without changelists containing the new data. This needs furt ...

Alt-tabbing out of a Standalone App or packaged version of a game does not trigger LostFocus or ReceiveFocus

Tools - Sep 9, 2015

If a user uses Alt-tab to change to another window, the ReceivedFocus and LostFocus functions are not called as they would usually be called when using something such as Shift+F1 or Ctrl+Esc. Note: ...

Certain UPROPERTY values are not updated during auto-recompile

UE - Gameplay - Blueprint - Aug 4, 2016

Sometimes manual recompile is required to make a blueprint actually recompile data-only changes, but not always. If the last manual compile was with default values, then changes are not updated. If ...

A Simulating Physics component with StartAwake = false will be awoken by a Welded component

UE - Simulation - Physics - Jan 10, 2025

A Simulating Physics component with StartAwake = false will be awoken by a Welded component If a welding occurs during the call to OnCreatePhysicsState, this breaks the start awake disabled flag. Th ...

Deploying from Windows to Linux fails on the first attempt

UE - Platform - Linux - Aug 3, 2017

After hitting this failure, if you try to deploy again, then it will work. This only occurs on the first attempt. Initially, I thought I hit a disc space issue I was hitting due to having a sample ...

Actor ClassID Value Read From Data Table only in PIE

UE - Gameplay - Blueprint - Sep 22, 2016

When accessing a data table in BP and getting an Actor Class from it the Class will return NULL when in Standalone Game, Launching, or in a packaged game. This only seems to work in PIE. ...

Particle disappears if it is using PSA_Velocity and setting custom time dilation 0

UE - Graphics Features - Dec 7, 2016

A licensee reported some of their particles disappear when setting the actor's custom time dilation 0. This seems to happen when a particle is using PSA_Velocity as Screen Alignment. This repros in ...

Draw as border is completely opaque when size in negative

UE - Editor - UI Systems - Feb 26, 2019

When an image widget is set to draw as border it will no longer render as a border if the size is negative. The widget appears completely opaque. ...

GetAllMobileRelevantLayerNames drops those layers which are only connected to RuntimeVirtualTextureOutput Node

UE - Graphics Features - May 6, 2021

in UMaterial::GetAllReferencedExpressions, the mobile branch ignores every CustomOutputExpressions including RuntimeVirtualTextureOutput. ...

Ensure after reparenting Blueprint and moving a property to the new parent

UE - Gameplay - Blueprint Editor - Jul 20, 2023

Moving a property from a recently reparented BP to its new parent will assert in  FBlueprintCompileReinstancer::MoveDependentSkelToReinst at  ensure(PrevStructSize == NewStructSize) This only see ...