In the level editor, when configuring a component that is part of an actor blueprint, adding entries to a TMap with C++ enum keys results in duplicate keys and an incorrect warning popup.

UE - Editor - Jan 22, 2026

Note: This started happening in UE 5.4 and persists up to latest. It is probably related to [Link Removed] Closed ([Link Re ...

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 ...

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 ...

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

UE - Runtime - Animation - 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 ...

When using Subversion (SVN) and Lock's comment is Japanese outside SourceControl, parsing of xml fails and Status may become NotControlled.

UE - Foundation - Core - Jun 28, 2019

If user lock assets with Japanese comments outside source control, XML acquired in svn status may contain Japanese strings, and XML parsing may fail and become NotControlled. This issue does not oc ...

Interchange GLTF importer truncates skeletal mesh bone influences to 4 per vertex

UE - Editor - Open File Formats - Aug 21, 2026

cf https://forums.unrealengine.com/t/interchange-gltf-importer-truncates-skeletal-mesh-bone-influences-to-4-per-vertex/2745391/2 Original message The UE5 Interchange GLTF importer appears to trunc ...

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. ...

[CrashReport] Assertion on Mac: Could not create a libwebsocket - FNetworkFileServerHttp::Init()

UE - Platform - Mobile - Jun 22, 2017

This is a common crash on Mac that occurs in the 4.16 release. This appears similar to [Link Removed], which was closed with the 4.13 release. Users have not provided descriptions. Many (but not a ...

[CrashReport] UE4Editor-UnrealEd.dylib!TBaseUObjectMethodDelegateInstance<false, UEditorEngine, TTypeWrapper<void> ()>::Execute()

UE - Platform - Apple - Nov 10, 2017

This is a longstanding but low frequency Mac crash. Users have not provided any descriptions of their actions when the crash occurred. Callstack from Log[2017.10.26-22.22.57:828][183]LogSavePackag ...

Attempting to export sequencer camera causes editor to crash on Linux

UE - Platform - Linux - Oct 26, 2016

Trying to export a sequence camera on Linux causes the editor to crash. This does not occur on Windows. EDIT: Crash seems to occur when focus leaves the FileName field. ...