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 ...

Niagara Position Mode Unset results in World Space rather than Local Space

UE - Niagara - Scripting - Apr 16, 2025

When an emitter's Position Mode is Unset, the particles spawn in World Space 0,0,0. This is unexpected. If the Position Mode is Unset in 5.4, the particles remain in Local Space, which is the inten ...

Interpolators of Particle Dynamic Parameters Need "nointerpolation".

UE - Niagara - Aug 1, 2019

Regardless Niagara or Cascade, dynamic parameters for particles are passed to pixel shaders from vertex shaders via InterpolantsVSToPS. It can cause a precision error on some materials, for example ...

[CrashReport] Linux crash - error VK_ERROR_EXTENSION_NOT_PRESENT

UE - Platform - Linux - Oct 27, 2017

This is an early trending Linux crash in 4.18, but also occurred in 4.17. It seems to occur before a project loads. Callstack from Log[2017.10.26-01.39.08:606][ 0]LogVulkanRHI: Display: - Found g ...

When an active Niagara Component is moved and reset+reactivated in the same frame, "Interpolated Spawning" causes "Spawn Burst Instantaneous" to spawn particles in the previous frame's outdated location

UE - Niagara - Mar 6, 2024

Consider a Niagara System with an Emitter in "Global Space" that has "Interpolated Spawning" active and a "Spawn Burst Instantaneous" module with a "Spawn Time" of 0.0 (for example, the built-in Con ...

sphere collision with start and end points set to the same value return no hit objects

UE - Gameplay - Aug 29, 2016

Sphere collision with start and end points set to the same value return no hit objects. Workaround Set the end vector to 1 away from the start vector (0,0,0 to 1,1,1, etc.) Regression (no) issue ...

[CrashReport] UE4Editor_ClothingSystemEditor!UClothingAssetFactory::CreateFromSkeletalMesh() [clothingassetfactory.cpp:357]

UE - Simulation - Physics - Character - Aug 21, 2017

This is a trending crash occurring in 4.17 and 4.17.1. Users have not provided any descriptions of their actions when the crash occurred. Source Context 345 if(Params.bTryAutoFix && Param ...

Soft angular constraints solve velocity like hard constraints

UE - Simulation - Physics - Jul 17, 2025

Soft 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 ...

Physics simulation shows strange behavior with specific skeletal mesh configurations

UE - Simulation - Physics - Mar 3, 2017

PhAT is inconsistent on when it does and doesn't apply scale to Constraint positions. This leads to cases where the positions provided create constraints that may not work when the Preview Skeletal ...

[CrashReport] Ongoing CollectGarbageInternal() assertion in 4.17

Tools - Aug 22, 2017

This callstack is occurring in 4.17.0 and 4.17.1, and appears to be a continuation of [Link Removed], which was fixed in 4.16.2 with CL 3502786. I'm not re-opening [Link Removed] because there are ...