Crash when using ComplexCollisionMesh and the ComplexCollisionMesh has more material index than drawing mesh's material index

UE - Simulation - Physics - Mar 2, 2020

When using ComplexCollisionMesh of StaticMesh asset, at the time of hit, the physical material refers to the material of the drawing mesh side using the material index of the collision mesh side. T ...

[CrashReport] FGenericPlatformMemory::OnOutOfMemory | TArray<FCompressedChunk,FDefaultAllocator>::ResizeTo

UE - Foundation - Core - Jul 20, 2017

This is a common crash affecting users in 4.16, and has occurred since at least 4.12 for more than 200 unique users. The callstack has similarities to [Link Removed], and as-such may be out of our ...

Blueprint fails to compile when adding new member to struct that is an input parameter of implemented interface function

UE - Gameplay - Blueprint - Jun 3, 2016

Adding variables to a structure that is an input parameter of an interface function causes a compile error in any blueprint that implements the interface until the interface is recompiled. Compile ...

Crash When Loading Cooked Material Assets in Editor Due to Shader Serialization

UE - Rendering Architecture - Shaders - Aug 27, 2025

In Unreal Engine 5.6+, the new shader serialization logic in FShaderMapResourceCode::Serialize does not correctly handle cooked assets that are loaded back into the editor (e.g., from a mounted .pak ...

TBaseBlendedCurve::ConvertToAdditive adds a curve track to an additive when the curve only exists in the base pose

UE - Anim - Runtime - May 29, 2023

When we create curves on additive animations, we are creating a curve based on whether the curve exists in either the base or additive pose.  This wouldn't be the expected behaviour for a user when ...

Materials with Subsurface Profile not affected by Opacity value

UE - Graphics Features - Oct 24, 2017

A material with Shading Model set to Subsurface Profile is no longer affected by Opacity value in 4.17, 4.18, and 4.19 (Main) but was previously working as intended in 4.16. This is a regression. ...

Reference to control rig can be lost on actors with multiple skeletal mesh components

UE - Anim - Rigging - Control Rig - Apr 4, 2023

In 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 ...

FUniqueNetIdRepl::NetSerialize() crashes when embedded in a TArray() of structs.

UE - Networking - Jun 29, 2020

Calling the NetSerialize() function of FUniqueNetIdRepl from a custom NetSerialize() causes a crash. This only seems to occur when the struct is part of an array RPC parameter. ...

Changing blueprint default values inside arrays only updates loaded child blueprints

UE - CoreTech - Jul 30, 2020

The 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 ...

Physics Asset primitives are being created with the default Name as None instead of BoneName_PrimitiveType

UE - Editor - Content Pipeline - Import and Export - Oct 27, 2024

When creating Physics Assets, either by automatic creation upon import, creation from skeletal meshes already in the project, or when we press Generate All Bodies (bottom right of a opened Physics A ...