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: ...

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 ...

Crash on Importing specific Animation Only FBX

Tools - Nov 16, 2015

When importing the attached FBX file with only Animations, the editor will crash. The Same asset will import without error in 4.9.2 Crash Reporter BUGG: [Link Removed] ...

In a Geometry Collection, enabling Nanite Fallback in a Nanite Enabled collection won't generate a Physics Body when Nanite is disabled

UE - Simulation - Physics - Destruction - Jun 30, 2025

In a Geometry Collection, enabling Nanite Fallback in a Nanite Enabled collection won't generate a Physics Body when Nanite is disabled. To verify this, follow the steps provided in the Steps to Re ...

Crash when spawning destructible objects in 2 player PIE

UE - Simulation - Physics - Destruction - Aug 31, 2016

Crash Reporter link: [Link Removed] With Source Context: [Link Removed] ...

HTTP If-None-Match response code is incorrect on Macintosh

Tools - Sep 22, 2016

Macintosh implementation for HTTP requests handle If-None-Match against ETags differently than Windows implementation. ...

BP - Nativization will fail at cook time if a BP class and a User-Defined Structure reference each other.

UE - Gameplay - Blueprint - Apr 20, 2017

Note: This happens with "Exclusive" nativization mode as well. This occurs because the nativized UDS 'GetDefaultValue()' method is generated into a .h file rather than a .cpp file. This creates a c ...

OnComponentWake Event does not trigger when the physical body is awoken by a Force

UE - Simulation - Physics - Feb 27, 2025

OnComponentWake Event does not trigger when the physical body is awoken by a Force. The steps described on Steps To Reproduce is enough to replicate this behavior. The OnComponentWake event is only ...

Interchange Runtime .glb Import Crash When Packaged

UE - Editor - Content Pipeline - glTF - Jun 10, 2025

The runtime import process works fine in editor, but fatal error when trying to do so with packaged build of project. My function that calls ImportAsset():bool UMeshLoader::RequestMeshLoad(FString ...

Crash during shader compilation when r.Shaders.Optimize=0

UE - Rendering Architecture - Shaders - Mar 11, 2024

The primary shader crashing is "FVisualizeLumenSceneCS" which I've put in the callstack section, but I think this is more likely a binding problem as I'm also see the following crash with cloud shad ...