"Build All Levels" does not re-AddNavigationSystemToWorld

UE - AI - Navigation - Feb 28, 2024

The Build All Levels editor action cleans up the world's NavDataSet (UNavigationSystemV1::NavDataSet) as pre-rebuild world cleanup by calling: SetNavigationSystem(nullptr); inside UWorld::Cleanu ...

Launching QAGame for HTML5 creates an 'uncaught exception: out of memory'.

UE - Platform - Mobile - Jan 18, 2017

Launching onto HTML5 opens the browser to Uncaught Exception: out of Memory After running it on a 64-bit browser, the following is printed:uncaught exception: abort("Cannot enlarge memory arrays. E ...

NiagaraSystem is compiled every time when first loaded in the editor

UE - Niagara - May 20, 2022

If you are using a large amount of Niagara, you will experience excessive load times in PIE even if nothing is changed. The following code change seems to be effective as an interim response. void ...

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: ...

Editing an array config property via ProjectSettings can end up editing other platform config properties.

UE - CoreTech - May 27, 2024

Platforms .ini config files can end up with incorrect data, due to how ProjectSettings manages the config data. On a Windows machine, if we open the ProjectSettings window, all the data is going to ...

[CrashReport] Mac crash - libobjc.A.dylib!objc_retain() [UnknownFile]

UE - Platform - Apple - Nov 10, 2017

This is a longstanding but low frequency Mac crash. User DescriptionsChanging camera shake values and testing in a new editor window Callstack from Log[2017.11.09-19.23.22:392][ 63]LogMaterial: Mi ...

Blueprints not marked dirty when variables in referenced actors are renamed

UE - Gameplay - Blueprint Compiler - Feb 20, 2018

Blueprints using renamed variable do not indicate that they need to be recompiled. (However errors are shown on play) It is possible to not see an error if you add a variable with the same name as ...

Niagara Scalability Crash When Processing Significance

UE - Niagara - Jun 4, 2025

Method FNiagaraScalabilityManager::ProcessSignificance() iterates on indices from Context.SignificanceIndices and uses them to access the State and ManagedComponents arrays. It can then decide to cr ...

Editor crashes when changing skeletal mesh if another skeletal mesh component is attached when using master pose node

OLD - Anim - Jan 27, 2020

The crash only occurs if the additional skeletal mesh component is used with Set Master Pose Component (see ToggleAttach function in the TopDownCharacter BP). It doesn't seem to matter what mesh we' ...

Set user focus for player 0 will cause other local players to lose input

UE - Gameplay - Input - Feb 28, 2019

When the player at index 0 sets its user focus it will cause other players to lose input. This does not occur when setting the user focus of players with an index higher than 0. ...