DebugEditor checkLockFreePointerList(TLS.NumPartial >= 0 && ((!!TLS.NumPartial) == (!!TLS.PartialBundle))) fails

UE - Foundation - Core - Feb 6, 2018

Occasionally, the Engine/Editor crashes on startup with an assertion in the lock-free void pointer list. ...

"Assertion failed: NumberOfFreeBits >= 0" on clients that attempt to connect to a server with the -NoPacketHandler option

UE - Networking - Oct 6, 2020

With the rework of IP address resolution in 4.25, this assert now occurs. When no packet handler is used, UPendingNetGame::InitNetDriver calls SendInitialJoin() immediately, before async address res ...

Exporting to FBx nanite staticmesh, export the low res fallback LOD 0

UE - Editor - Open File Formats - Import and Export - Dec 7, 2022

The exporter export the render data and the nanite render data is on the gpu and is not accessible, this is why it export the fallback mesh. Its more complex then it appear since we will need to do ...

Importing a 16x16km landscape at 0.5m resolution crashes Unreal (not enough VRAM)

UE - Graphics Tools - Terrain - Landscape - Jan 9, 2023

FBX Import - Morph target normals not correctly applied when imported as LOD 0

UE - Editor - Open File Formats - FBX - Nov 27, 2025

This is a regression since 5.5 with skeletal meshes where morph target normal/tangent deformation only works when a mesh is imported as a LOD of an existing skeletal mesh, but not when imported as L ...

[CrashReport] Crash on FMaterialEditor::OnCanPromoteToParameter()

UE - Rendering - Architecture - Materials - Jun 22, 2017

This is a common crash in the 4.16 release (affecting Windows and Mac). A log file is attached. Users have not provided descriptions so additional information is not currently available. Windows C ...

[CrashReport]UnrealEditor-Chaos!Chaos::TEventContainer<Chaos::FCollisionEventData>::DispatchConsumerData() [EventManager.h:214]

UE - Runtime - Simulation - Mar 14, 2022

Generated from CrashReporter Error Messages:Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Containers\Array.h] [Line: 691] Array ind ...

Bounds location of apex destructible mesh will not be updated when added to sequencer directly from content browser

UE - Simulation - Physics - Destruction - Apr 22, 2020

Destructible mesh's location will not be updated when added to sequencer directly from content browser, unless two different locations are keyed on the transform track of the mesh. We found the bug ...

Ragdoll replication on server side is not replicated correctly on client

UE - Networking - Dec 2, 2014

Ragdoll replication on server side is not replicated correctly on client. The client will see the server players ragdoll dissappear and reappear at the 0,0,0 origin point. AnswerHub Posts: https: ...