Unreal Engine Issues
Unreal Engine Issues
LayeredBlendPerBone without BlendRootMotionBasedOnRootBone exaggerates root motion
UE - Runtime - Animation - May 27, 2023When BlendRootMotionBasedOnRootBone is false, the LayeredBlendPerBone is aggregating root motion of the child poses ontop of the base pose root motion. (ie. if the first child pose's blend weight i ...
Prevent unnecessary rebuilds of windows resource files
UE - Foundation - Cpp Tools - UnrealBuildTool - Sep 20, 2023How Necessary are BUILT_FROM_CHANGELIST and BUILD_VERSION in Resource Files? We've been investigating ways to improve the speed of our iterative engine builds, and have found that the vast, vast maj ...
Niagara Mesh Renderer registers NumParticles x NumMeshVariants TLAS instances
UE - Rendering - Graphics Features - Ray Tracing - May 28, 2026When using the Niagara Mesh Renderer with multiple mesh variants selected via MeshIndex, the number of TLAS instances allocated is NumParticles × NumMeshVariants and enabling the Path Tracer can ca ...
Client Gameplay Effect stuck on due to duplicate ReplicationIDs
UE - Gameplay - Gameplay Ability System - Oct 31, 2025We've been tracking down a problem recently with the Gameplay Ability System where a gameplay effect is properly removed on the server, but the client has the gameplay effect stuck on permanently. ...
[AI] Gaps between Nav Mesh tiles in World Partition map causing movement issues
UE - AI - Navigation - Nov 4, 2025Navmesh has seams between some tiles that are actual edges rather than previously found "gaps" where it was a debug rendering issue. Pathfinding does fail between these tiles to go straight across. ...
[CrashReport] Mac crash - UE4Editor-Slate.dylib!FTextLayout::GetAsTextAndOffsets()
UE - Platform - Apple - Aug 15, 2017This is a trending Mac crash in 4.17.0 that also had some occurrence in 4.16. Users have not provided any descriptions of their actions when the crash occurred, but the callstack is nearly identica ...
In some situations, a Blueprint can become devoid of an Event Graph. While no graphs are present, multiple variables can be created with the same name.
UE - Framework - Blueprint Editor - Aug 26, 2024In some situations, a Blueprint can become devoid of an Event Graph, or be created without one from the start. For example, function "FKismetEditorUtilities::CreateBlueprint()" in UE 5.4 does not ca ...
Hot reload causes placed actor to lose variable references
UE - Foundation - Cpp Tools - Hot Reload - Nov 9, 2017Preforming a hot reload causes placed actors to lose code based variable settings. More repro steps: 1. Open UE4Editor.exe 2. Create a First Person Code project 3. Build the project for Developme ...
AddOrUpdateWarpTargetFromComponent behaving incorrectly when using a SceneComponent with non-identity scale
UE - Anim - Gameplay - Jul 15, 2025When using AddOrUpdateWarpTargetFromComponent you can pass in a SceneComponent, Relative Location and Rotation as well as optionally choosing to have the warp target follow the object if it moves.If ...
Assertion failed in FAudioDevice::UnregisterSoundClass when GC
UE - Audio - Aug 13, 2018The licensee reported that check(IsInAudioThread()) was failed in FAudioDevice::UnregisterSoundClass when GC. The following is the call stack: 1 #00 pc 030d7b58 libUE4.so HandleError (/home/pirates ...