Unreal Engine Issues
Unreal Engine Issues
UBT compiler output is garbled when run via UAT (Japanese system locale)
UE - Core - Cpp Tools - Oct 2, 2026When UnrealBuildTool (UBT) is launched by UAT, for example by RunUAT.bat BuildCookRun build, localized (Japanese) MSVC error messages show up garbled in the console and in UAT's Log.txt. The UBT log ...
SKP import - Materials missing and incorrect when using Collapse all
TM - Interoperability - Sep 30, 2026Reported in SF [Link Removed] When importing a .skp model into Twinmotion 2026.2 Preview as Geoemtry, using the Collapse all mode will cause materials to be displayed incorrectly, replacing most ma ...
Mutable Chaos Cloth breaks when culling mesh affects mesh sections with cloth
UE - Runtime - Mutable - Sep 29, 2026Encountering an issue since we updated to UE5.8 where characters whose cloth mesh sections have vertices culled will cause mesh degradation in editor and crashes in packaged builds. There are two i ...
GPU Scene reserved resources can break Niagara mesh preview rendering
UE - Rendering - Architecture - Niagara - Sep 28, 2026When a Niagara emitter has multiple Mesh Renderers and each renderer draws a different subset of particles (via Renderer Visibility), all renderers are drawn using the color of particle index 0 in t ...
Particle Random Value is the same for all particles with a Niagara Mesh Renderer
UE - Rendering - Architecture - Niagara - Sep 28, 2026A material using the Particle Random Value node returns the same value for every particle drawn by a Niagara Mesh Renderer. Particle transforms are not affected, only the random value. This happens ...
[Niagara][5.8] Data Channel Read and Write register with an identical type hash when fx.Niagara.DataChannels.Enabled is set from ini, hitting checkf in FNiagaraTypeRegistry::RegisterTypeInternal
UE - Rendering - Architecture - Niagara - Sep 28, 2026Affects: 5.8 (verified on Release-5.8), Windows, EditorSummary Adding fx.Niagara.DataChannels.Enabled=true to an ini file makes the Niagara editor assert when a Data Channel Read is created. The sa ...
Light Function and Post Process domain material thumbnails show the default material
UE - Rendering - Architecture - Materials - Sep 25, 2026Since 5.8, materials whose Material Domain is Light Function or Post Process no longer preview correctly in the editor. They render as the default material (WorldGridMaterial) instead of the materia ...
ResolvedView.DirectionalLightColor and DirectionalLightDirection go black when one of several directional lights is removed from the scene
UE - Rendering - Features - Sep 25, 2026With more than one directional light in the scene, ResolvedView.DirectionalLightColor and ResolvedView.DirectionalLightDirection can report the wrong light, or black and a zero vector, while a direc ...
Update prepackaged dotnet to latest 10 patch release due to crash on Mac OS.
UE - Platform - Mac - Sep 24, 2026A dotnet crash occurs sporadically with a sigsev or sigbus when running on Mac OS. This is in the dotnet executable itself, and can happen on commands like `dotnet build`, not just on executing the ...
Editor hangs for several seconds when closing multiple asset editors
UE - Editor - Sep 24, 2026CL 51680020 added an async write in SStandaloneAssetEditorToolkitHost::SaveTabLocation(). This can cause multi-threaded write conflicts on EditorPerProjectUserSettings.ini. As a result, the file mov ...