Crash Importing some assets with "Keep Overlapping Vertex"

UE - Editor - Content Pipeline - Import and Export - Nov 29, 2016

Download offending asset here: [Link Removed] Error message: Assertion failed: NewPosition >= 0 [Link Removed] [Line: 452] Source Context: 438 virtual ~FFileHandleWindows() 439 ...

Build failure after nativizing any child Blueprint class with function override (regression).

UE - Gameplay - Blueprint - Jun 7, 2018

Nativization regression in 4.20 preview 1. Cannot nativize overridden functions. Log Output:UATHelper: Packaging (Windows (64-bit)): D:/Projects/Unreal/NativizeMethod/Intermediate/Plugins/Nativized ...

FAnimationRuntime::BlendPosesPerBoneFilter() causes an assertive crash when Skeletal Mesh LOD is changed

UE - Anim - Runtime - Nov 1, 2023

The crash occurs from "check(BoneBlendWeights.Num() == NumBones);" This crash occurs when the following conditions are met;The skeletal mesh LOD is changed.The number of bones is difference between ...

Editor Crashes When Duplicating Actor that Contains Additional Components

UE - Gameplay - Dec 11, 2015

Attempting to spawn a copy of an actor that has components that were added to an instance of that actor in the level causes a crash. Spawning the actor without adding additional components to the in ...

Imported heightmaps with 2x2 sections crash editor

UE - LD & Modeling - Terrain - Landscape - Jul 18, 2016

Importing a heightmap with 2x2 segments seems to cause the editor to crash in 3 different instances: 1. Importing the same 2x2 segment landscape a second time after deleting the first instance 2. ...

Editor Crashes When Updating Captures on Sphere Reflection Captures

UE - Graphics Features - Feb 20, 2017

Error message: Assertion failed: (Index >= 0) & (Index < ArrayNum) [Link Removed] [Line: 633] Array index out of bounds: -1 from an array of size 11 Source Context: 200 CubemapArray.Updat ...

HZB Occlusion causes large stalls on the render thread

UE - Rendering Architecture - RHI - Oct 7, 2025

HZB Occlusion causes large stalls (greater than 5ms seen) on the render thread due to an RHI flush. This is caused by the following code in FDynamicRHI::RHIMapStagingSurface_RenderThread which force ...

Form Extended Structures will only destroy one mesh but not any attached

UE - Simulation - Physics - Destruction - Nov 28, 2014

DESCRIPTION: While using form extended structures enabled for a Destruction mesh one of the meshes will be able to be damaged while any others attached will not fracture or damage at all. For exam ...

Actors in sublevels do not replicate to Clients after Seamless ServerTravel

UE - Networking - Dec 9, 2015

Actors in sublevels do not replicate to Clients after Seamless ServerTravel. The user reporting this noted that "[...] UNetDriver::IsLevelInitializedForActor() keeps returning false even when the ac ...