IsTraceHandleValid with default FTraceHandles has unexpected behavior on the first frame

UE - Simulation - Physics - Sep 18, 2018

Because both FWorldAsyncTraceState's CurrentFrame and FTraceHandle are default initialized to 0, on the first frame, if a new Asnc Trace starts all default FTraceHandles will reference the same (now ...

RGB/UINT10 HDR Format not using ST.2084

UE - Rendering Architecture - RHI - Aug 23, 2021

Specification here: [Link Removed] Which is mirrored in engine in FD3D12DynamicRHI::Init (for example): [Image Removed] However, FWindowsPlatformMisc::ChooseHDRDeviceAndColorGamut always returns ...

When ControlRig.EnableAnimNodePerformanceOptimizations is enabled, the default pose briefly appears after the Control Rig is reinitialized

UE - Anim - Rigging - Control Rig - Sep 1, 2025

Since UE5.6, ControlRig.EnableAnimNodePerformanceOptimizations is enabled by default, and this appears to be causing the issue. Specifically, when the control rig’s construction event is processed, ...

The LightMixer window is making all scene lights visible once you toggle the visibility of a single light

UE - Virtual Production - Tools - Jul 31, 2025

The LightMixer window is making all scene lights visible once you toggle a single light as visible. Any light source (except SkyLight) will be turn visible once a single light is made visible using ...

"Failed to find object 'Class None'" in project log after creation

UE - Foundation - Core - Nov 17, 2014

Users reported seeing the line "LogUObjectGlobals:Warning: Failed to find object 'Class None.'" in the Output log after creating a project. I was able to confirm in a new blank code project without ...

Spawn Emitter At Location is not available in an Object Blueprint

UE - Gameplay - Blueprint - Feb 4, 2015

Spawn Emitter At Location is no longer an available node in an Object Blueprint. It was available in 4.6.1 but is not in 4.7 or 4.8. Spawn Emitter Attached is still available in an Object BP. Teste ...

Execution reroute nodes become wildcard reroute nodes when creating a second reroute node off the same execution pin

UE - Gameplay - Blueprint - Sep 21, 2015

Execution reroute nodes become wildcard reroute nodes when creating a second reroute node off the same execution pin. Note: this does not appear to affect their functionality as execution reroute no ...

The packaged folder for a Linux project is more than twice the size of a windows folder

UE - Platform - Linux - Aug 22, 2016

LinuxNoEditor folder from a packaged Linux game is more than double the size of a packaged Windows project folder (WindowsNoEditor). Results from packaging an empty Third Person Project Windows (6 ...

Using GENERATED_BODY() instead of GENERATED_UINTERFACE_BODY() in an Interface code class results in a UHT crash when trying to build the project.

UE - Foundation - Core - Mar 3, 2015

Replacing GENERATED_UINTERFACE_BODY() with GENERATED_BODY() in 4.7.0 or above results in an Unreal Header Tool crash and build failure in Visual Studio. This was working in 4.6.1, but when tested i ...

Enabling "Support Deferred Rendering with Metal" Crashes on IOS device

UE - Platform - Mobile - Feb 8, 2017

After enabling "Support Deferred Rendering with Metal" and then launching to an IOS device (in this case iphone 6+) the game will no longer open and run. REGRESSION? Yes Worked in Binary 4.13.2 C ...