Unreal Engine Issues
Unreal Engine Issues
Lumen Card Sharing is active on material with custom primitive data
UE - Graphics Features - Lumen - Aug 13, 2025The wrong emissive value may be used on Nanite objects with custom primitive data when Lumen card sharing is enabled. This issue can be mitigated with: r.LumenScene.SurfaceCache.AllowCardSharing 0 ...
GPU Crash from out of memory read/writes in Lumen when using non-power-of-2 TracingOctahedronResolution
UE - Graphics Features - Lumen - Aug 6, 2025When the r.Lumen.ScreenProbeGather.TracingOctahedronResolution is not a power of 2 or LumenFinalGatherQuality in a Post Processing Volume is set to a value such that the TracingOctahedronResolution ...
Crash when displaying lumencards on map with many objects
UE - Graphics Features - Lumen - Aug 1, 2025There is a thread conflict between FRDGBuilder execution in Background Worker and LumenVisualizer's LumenCard add/delete process. When lumen cards are displayed in a scene with many objects, a crash ...
Hardware Raytracing on Lumen can cause a crash on AMD Radeon GPUs
UE - Graphics Features - Lumen - Jul 29, 2025Hardware Raytracing support can cause a crash on AMD Radeon GPUs when creating the RT pipeline state. ...
Niagara mesh particles invalidate lighting when "Cast Shadow" is enabled with Hardware Ray Tracing enabled
UE - Graphics Features - Lumen - Jun 24, 2025Lumen HWRT, combined with Niagara Mesh Renderer, can cause the Lumen Scene to be reset, resulting in a sudden change to indirect lighting. ...
DiffuseIndirect_Lumen_3 parameter missing and causing crash with Screen Space reflections and Lumen Async Compute
UE - Graphics Features - Lumen - May 3, 2025When the Reflection Method is set to Screen Space and Lumen reflections async compute is enabled Unreal will crash because DiffuseIndirect_Lumen_3 parameter missing, due to how DenoiserOutputs are o ...
Divergent group barriers in Lumen
UE - Graphics Features - Lumen - Apr 23, 2025Intel reported GPU crashes on their hardware caused by divergent group barriers in ScreenProbeConvertToIrradianceCS:[numthreads(THREADGROUP_SIZE, THREADGROUP_SIZE, 1)] void ScreenProbeConvertToIrra ...
NVIDIA 5080 GPU Crash when launching City Sample with DX12
UE - Graphics Features - Lumen - Apr 16, 2025UPDATE This issue no longer reproduces on driver versions 580.88 and higher. City Sample game crashes immediately upon opening with a NVIDIA 5080 with the latest drivers as well as some previous dr ...
Lack of multi-bounce when using software traced lumen radiosity
UE - Graphics Features - Lumen - Apr 4, 2025Certain Lumen Hardware Ray Tracing CVars, when disabled in isolation, will not fall back to tracing the Global Distance Field, because the Global Distance Field is still disabled. The function "Lum ...
Skylighting on distant objects causes severe flickering with Lumen
UE - Graphics Features - Lumen - Mar 31, 2025Lighting on distant meshes flickers when using Lumen and Skylights. Turning Lumen off and lighting from the skylight is stable. Turning off Lumen screen traces also lowers the amount of flickering ...