Unreal Engine Issues
Unreal Engine Issues
FBX reimport issue with Interchange Framework
UE - Editor - Content Pipeline - Import and Export - Sep 15, 2025A licensee has reported that the following repro steps can result in a "Failed to merge bones" error:One of our Skeletal Mesh assets was imported into engine version 5.4 using an older version of th ...
Multi Sphere Trace is not returning the correct Impact Location
UE - Simulation - Physics - Jan 19, 2015Multi Sphere Trace is not returning the correct Impact Location. Other AnswerHub Report:https://answers.unrealengine.com/questions/30952/multisphere-trace-fhitresult-location-same-as-impa.html ...
[CrashReport] UE4Editor_HotReload!`FHotReloadClassReinstancer::UpdateDefaultProperties'::`2'::FPropertyValueMemoryWriter::operator<<() [hotreloadclassreinstancer.cpp:372]
UE - Foundation - Core - UObject - Sep 14, 2017This is a common crash that has occurred for users since at least 4.16. User DescriptionsUsing the PIE i compiled some c++ then quit the PIE before the end of the compilation. Source Context 35 ...
Error on Loading Pawn Blueprint Containing ActorSequenceComponent from GameMode Constructor
UE - Anim - Sequencer - Oct 25, 2017When attempting to load a Blueprint that contains a ActorSequence component from inside of a Gamemode's constructor, errors are given. The ActorSequence component is also removed from the Blueprint ...
Build Plugin process fails with null reference exception when building a plugin that has "Can Be Used With Unreal Header Tool" set to true
UE - Foundation - Cpp Tools - Dec 18, 2018Trying to use UAT to build a plugin that has CanBeUsedWithUnrealHeaderTool set to true will fail due to a null reference exception (log from Main CL 4666322 attached). This happens because the plugi ...
Adding an Object to a Plugin using the C++ Class Wizard results in a compilation error.
UE - Foundation - Core - Jan 10, 2019Adding an Object class to a plugin's module using the C++ Class Wizard results in a compilation error due to attempts to edit the new class' generated.h file during the initial compilation attempt. ...
Comment Box Edges/Corners Do Not Precisely Follow Cursor when Resizing
UE - Editor - UI Systems - Slate - Oct 10, 2017When resizing comment boxes, the edges/corners do not follow the cursor precisely, especially when the cursor is moved around quickly. On Windows, the cursor will either get ahead of the box or ins ...
Niagara Regression - Looping particle with Spawn Burst Instantaneous on time 0.0 flickers for a frame between loops
UE - Niagara - Jul 16, 2025Note: This worked correctly up to UE 5.4, but repros from UE 5.5 up to mainline latest. If a Niagara Emitter is set up with "Spawn Burst Instantaneous" on time 0.0, and the spawned particle(s) have ...
Missing PSO Precaches in the engine
UE - Rendering - Architecture - RHI - Aug 20, 2025A licensee wanted to report some missing PSO Precaching they found, which they have fixed locally: 1. UCableComponent doesn't implement CollectPSOPrecacheData or call CheckPSOPrecachingAndBoostPri ...
Adding/Removing a Material Layer on a Parent Material doesn't propagate to Children correctly
UE - Rendering - Architecture - Materials - Jun 9, 2026When a Material Layer is added to or removed from a Parent Material the layer changes don’t automatically propagate to Child Materials correctly even if the Parent Material is saved. The Child mate ...