There 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 is likely to occur.
A workaround is to use the console command "r.RDG.
1. Open Big_City_LVL map with CitySample project
2. Input r.Lumen.Visualize.CardPlacement 1 to display the LumenCard
3. Crashes when moving the camera or unloading the level
LoginId:591090904d604e5548a85aad383ffb67 EpicAccountId:fb567da00f03436dabdb32db92746435Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Containers\Array.h] [Line: 783] Array index out of bounds: 179235 into an array of size 179235 UnrealEditor_Renderer!VisualizeCardPlacement() [D:\build\++UE5\Sync\Engine\Source\Runtime\Renderer\Private\Lumen\LumenVisualize.cpp:1304] UnrealEditor_Renderer!FDeferredShadingSceneRenderer::LumenScenePDIVisualization() [D:\build\++UE5\Sync\Engine\Source\Runtime\Renderer\Private\Lumen\LumenVisualize.cpp:1505] UnrealEditor_Renderer!FDeferredShadingSceneRenderer::BeginInitViews() [D:\build\++UE5\Sync\Engine\Source\Runtime\Renderer\Private\SceneVisibility.cpp:5733] UnrealEditor_Renderer!FDeferredShadingSceneRenderer::Render() [D:\build\++UE5\Sync\Engine\Source\Runtime\Renderer\Private\DeferredShadingRenderer.cpp:1614] UnrealEditor_Renderer!RenderViewFamilies_RenderThread() [D:\build\++UE5\Sync\Engine\Source\Runtime\Renderer\Private\SceneRendering.cpp:5431] UnrealEditor_Renderer!`UE::RendererPrivateUtils::Implementation::TPersistentBuffer<UE::HLSL::FCellBlockData,UE::RendererPrivateUtils::Implementation::FStructuredBufferTraits>::ValidateGPUData<`FSceneCullingBuilder::UploadToGPU'::`51'::<lambda_1> >'::`12'::<l() [D:\build\++UE5\Sync\Engine\Source\Runtime\Renderer\Private\SceneRendering.cpp:5734] UnrealEditor_RenderCore!`FRenderCommandPipeRegistry::StopRecording'::`2'::<lambda_1>::operator()() [D:\build\++UE5\Sync\Engine\Source\Runtime\RenderCore\Private\RenderingThread.cpp:1541] UnrealEditor_RenderCore!TGraphTask<TFunctionGraphTaskImpl<void __cdecl(void),1> >::ExecuteTask() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Async\TaskGraphInterfaces.h:634] UnrealEditor_Core!UE::Tasks::Private::FTaskBase::TryExecuteTask() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Tasks\TaskPrivate.h:504] UnrealEditor_Core!FNamedTaskThread::ProcessTasksNamedThread() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Private\Async\TaskGraph.cpp:779] UnrealEditor_Core!FNamedTaskThread::ProcessTasksUntilQuit() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Private\Async\TaskGraph.cpp:668] UnrealEditor_RenderCore!RenderingThreadMain() [D:\build\++UE5\Sync\Engine\Source\Runtime\RenderCore\Private\RenderingThread.cpp:317] UnrealEditor_RenderCore!FRenderingThread::Run() [D:\build\++UE5\Sync\Engine\Source\Runtime\RenderCore\Private\RenderingThread.cpp:443] UnrealEditor_Core!FRunnableThreadWin::Run() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Private\Windows\WindowsRunnableThread.cpp:159]
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-308802 in the post.
| 0 |
| Component | UE - Graphics Features - Lumen |
|---|---|
| Affects Versions | 5.5 |
| Target Fix | 5.7 |
| Created | Aug 1, 2025 |
|---|---|
| Updated | Aug 14, 2025 |