Unreal Engine Issues
Unreal Engine Issues
Float Curve evaluation may yield completely wrong results due to floating-point precision issue
UE - Runtime - Animation - Oct 31, 2024Note: This is possibly related to [Link Removed] To Do . For some inputs, function UE::Curves::WeightedEvalForTwoKeys() ins ...
Soft angular constraints solve velocity like hard constraints
UE - Runtime - Simulation - Jul 17, 2025Soft angular constraints are solving velocity like hard constraints. Instead of swinging back and forth, the affected body just snaps to 45 degrees. Check the steps to reproduce for more details. Th ...
Reference to control rig can be lost on actors with multiple skeletal mesh components
zComponent - Archive - Apr 4, 2023In the attached project, when we initially add a control rig track for the actor with multiple skeletal mesh components, we add the control rig for the correct component because FControlRigParameter ...
Changing blueprint default values inside arrays only updates loaded child blueprints
UE - Core - Systems - Jul 30, 2020The rules for delta serialization in UE4 are complicated, and the editor tries to hide them from you, which works 90% of the time but can lead to confusion and data loss in other situations. In the ...
[CrashReport] Assertion failed: TaskDataArray.Num() == Exporter->VolumetricLightmapTaskGuids.Num()
UE - Graphics Features - Lumen - Oct 2, 2017This is a trending crash coming out of the 4.18 Previews. Users have not provided any descriptions of their actions when the crash occurred, but at least two of the affected projects are being creat ...
Cannot select child anim BPs for use in linked anim layers
UE - Runtime - Animation - Jul 15, 2021From UDN: [Link Removed] Unable to set a Child ABP with inherited interface to a Linked Animation Layer Instance Class. I have a ABP_Biped which is our main ABP. I have the locomotion (idle+straf ...
Instanced Static Meshes ignore max World Position Offset Displacement for bounds after UpdateInstanceTransform is called
UE - Rendering - Graphics Features - Jun 18, 2025When an Instanced Static Mesh Component (ISMC) uses a material with a non-zero Max World Position Offset Displacement, the bounds are correctly expanded at initialization. However, after calling Upd ...
Render target size mistmatch in ShaderDrawDebug
UE - Graphics Features - Jun 9, 2020We found a d3d debug validation assert in RDG_EVENT_NAME("ShaderDrawDebug"), with the full DLSS integration. It however also reproduces in (4.25.1-release, dev-rendering and the plugin branch with ...
Wrong density calculation in UBodySetup::CalculateMass
UE - Runtime - Simulation - Sep 29, 2025Wrong density calculation in UBodySetup::CalculateMass. The licensee has provided the following analysis and suggested fix: In UBodySetup::CalculateMass, the following code is present: // physical ...
Unwanted black boundaries are displayed in a vertical split-screen with 3 players.
UE - Gameplay - Dec 2, 2019Floating point error from UGameViewportClient::SplitscreenInfo causes this issue. FMath::TruncToInt( 3240 /*ViewportSize*/ * 0.333f/*Ratio in SplitScreenInfo*/ ) = 1079 I suggested a following t ...