Import then cancel while file is read leads to potential crash

TM - Interoperability - Oct 6, 2025

1/ Import a file with mootools such as an fbx 2/ while the file is still read, cancel the import Result : may crash few times after (when theoretically the file has finished being read) - not repr ...

Crash in FMaterialUtilities::CreateFlattenMaterialInstance when building Simplified HLOD layer

UE - World Creation - Worldbuilding Tools - HLOD - Aug 17, 2022

From licensee: The issue here starts in FVoxelizeMeshMerging::ProxyLOD() where the FlattenMaterial created using FMaterialUtilities::CreateFlattenMaterialWithSettings() returns an empty struct. I d ...

Level editor viewports crash when deleting actors after a layout change

UE - Editor - Workflow Systems - Apr 18, 2022

Reported by a customer while testing USD import. See additional URL ...

[AI] Crash while loading navmesh with async static mesh compilation enabled

UE - AI - Navigation - Jun 16, 2022

I tried 10+ times but am unable to get this to reproduce locally. Licensee reports that this is a rare crash for them. ...

UMG - Drag/Drop crash on exit when dropping back onto an old slot.

UE - Editor - UI Systems - Jan 7, 2015

When dragging and dropping a widget onto an old slot, it resulted in a crash on exit. ...

Clicking "Pause on Impact" with in the details of the InterpToMovement component will cause a crash

UE - Gameplay - Blueprint - Apr 30, 2015

When checking the "Pause on Impact" check box within the details panel for the InterpToMovement component, the editor crashes ...

[CrashReport] Mac crash - libobjc.A.dylib!objc_retain() [UnknownFile]

UE - Platform - Apple - Nov 10, 2017

This is a longstanding but low frequency Mac crash. User DescriptionsChanging camera shake values and testing in a new editor window Callstack from Log[2017.11.09-19.23.22:392][ 63]LogMaterial: Mi ...

Crash in FTickFunction::RegisterTickFunction

UE - Gameplay - Jan 31, 2017

Per https://udn.unrealengine.com/questions/319627/uworldspawnactor-with-template-parameter-causes-cr.html ...

Switching raytracing console variable in runtime can crash engine.

UE - Graphics Features - Lumen - May 13, 2020

Licensee reported that is caused by missing ECVF_RenderThreadSafe flag in these console variable definitions. r.RayTracing.Shadows r.RayTracing.AmbientOcclusion r.RayTracing.Reflections Here is a ...

Static lighting crash on 5.4 when using landscape with WPO

UE - Graphics Tools - Terrain - Landscape - May 22, 2024

When static lighting is built for a landscape with "Use Material Position Offset in Static Lighting" enabled it causes an editor crash. Licensee mentioned it was likely caused by a commit for 5.4, C ...