UE 5.5 MegaLights

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1

UE 5.5. with projects, that contains MegaLight light sources always crushes.

When I tried to start my personal level - engine has crushed. So i’ve desided to change EditorStartupMap to default ThirdPersonMap in DefaultEngine.ini to be sure that the problem is in level itself and default level starts well. Then i’ve tried to load my custom level throug Content Drawer and… engine has crushed. So once again i’ve start the engine with the default level and delete all the light souces from my BP’s through Content Drawer. One more time I’m trying to start my custom level and it works! Thats how i understood, that the problem is in MegaLights.

LogWindows: Failed to load ‘aqProf.dll’ (GetLastError=126)
LogWindows: File ‘aqProf.dll’ does not exist
LogProfilingDebugging: Loading WinPixEventRuntime.dll for PIX profiling (from …/…/…/Engine/Binaries/ThirdParty/Windows/WinPixEventRuntime/x64).
LogWindows: Failed to load ‘VtuneApi.dll’ (GetLastError=126)
LogWindows: File ‘VtuneApi.dll’ does not exist
LogWindows: Failed to load ‘VtuneApi32e.dll’ (GetLastError=126)
LogWindows: File ‘VtuneApi32e.dll’ does not exist
LogWindows: Started CrashReportClient (pid=10736)
LogWindows: Enabling Tpause support
LogWindows: Custom abort handler registered for crash reporting.

So can anyone help me to understand how to use this MegaLigths without engine crushing ?

2

Same problem:

LoginId:9a6bbc12425d311aaffc8190d4d9bf76
EpicAccountId:2b3f513183a14cff82d9d68cd6941c47

Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0x0000000000000008

UnrealEditor_Renderer
UnrealEditor_Renderer
UnrealEditor_Renderer
UnrealEditor_Renderer
UnrealEditor_Renderer
UnrealEditor_RenderCore
UnrealEditor_RenderCore
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_RenderCore
UnrealEditor_RenderCore
UnrealEditor_Core
UnrealEditor_Core
kernel32
ntdll

LOG:
[2024.11.26-16.01.53:876][307]LogWindows: Error: === Critical error: ===
[2024.11.26-16.01.53:876][307]LogWindows: Error:
[2024.11.26-16.01.53:876][307]LogWindows: Error: Fatal error!
[2024.11.26-16.01.53:876][307]LogWindows: Error:
[2024.11.26-16.01.53:876][307]LogWindows: Error: Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0x0000000000000008
[2024.11.26-16.01.53:876][307]LogWindows: Error:
[2024.11.26-16.01.53:876][307]LogWindows: Error: [Callstack] 0x00007ffc12dc8080 UnrealEditor-Renderer.dll!UnknownFunction
[2024.11.26-16.01.53:876][307]LogWindows: Error: [Callstack] 0x00007ffc130bad77 UnrealEditor-Renderer.dll!UnknownFunction
[2024.11.26-16.01.53:876][307]LogWindows: Error: [Callstack] 0x00007ffc129fccb9 UnrealEditor-Renderer.dll!UnknownFunction
[2024.11.26-16.01.53:876][307]LogWindows: Error: [Callstack] 0x00007ffc137d4b26 UnrealEditor-Renderer.dll!UnknownFunction
[2024.11.26-16.01.53:876][307]LogWindows: Error: [Callstack] 0x00007ffc1378bb8a UnrealEditor-Renderer.dll!UnknownFunction
[2024.11.26-16.01.53:876][307]LogWindows: Error: [Callstack] 0x00007ffc27a5b7c5 UnrealEditor-RenderCore.dll!UnknownFunction
[2024.11.26-16.01.53:876][307]LogWindows: Error: [Callstack] 0x00007ffc27a894cf UnrealEditor-RenderCore.dll!UnknownFunction
[2024.11.26-16.01.53:876][307]LogWindows: Error: [Callstack] 0x00007ffc27fe2722 UnrealEditor-Core.dll!UnknownFunction
[2024.11.26-16.01.53:876][307]LogWindows: Error: [Callstack] 0x00007ffc27fd7d4a UnrealEditor-Core.dll!UnknownFunction
[2024.11.26-16.01.53:876][307]LogWindows: Error: [Callstack] 0x00007ffc27fd81ee UnrealEditor-Core.dll!UnknownFunction
[2024.11.26-16.01.53:876][307]LogWindows: Error: [Callstack] 0x00007ffc27ab7e1c UnrealEditor-RenderCore.dll!UnknownFunction
[2024.11.26-16.01.53:876][307]LogWindows: Error: [Callstack] 0x00007ffc27abceb4 UnrealEditor-RenderCore.dll!UnknownFunction
[2024.11.26-16.01.53:876][307]LogWindows: Error: [Callstack] 0x00007ffc2860c0ad UnrealEditor-Core.dll!UnknownFunction
[2024.11.26-16.01.53:876][307]LogWindows: Error: [Callstack] 0x00007ffc286035cf UnrealEditor-Core.dll!UnknownFunction
[2024.11.26-16.01.53:876][307]LogWindows: Error: [Callstack] 0x00007ffcc108e8d7 KERNEL32.DLL!UnknownFunction
[2024.11.26-16.01.53:876][307]LogWindows: Error:

3

I also get the exact same error.

If I go into DefaultConfig.ini and turn he Megalights flag to FALSE the projects runs fine.

If I switch it to TRUE the engine crashes when I try PIE, and after that whenever I open the project.

4

If you use a directional light, then this may cause a crash. since the directional light source does not work with Megalight yet

5

In my project copy I tried deleting the directional light to see if it fixed things, but as soon as i hit play for PIE it crashes.

After this it always crashes shortly after opening until I disable the Megalights flag,

The error is exactly as JRFernande, but I have debugger symbols installed so it’s more detailed:

Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0x0000000000000008

UnrealEditor_Renderer!LightFunctionAtlas::BindGlobalParameters() [D:\build++UE5\Sync\Engine\Source\Runtime\Renderer\Private\LightFunctionAtlas.cpp:990]
UnrealEditor_Renderer!FDeferredShadingSceneRenderer::RenderMegaLights() [D:\build++UE5\Sync\Engine\Source\Runtime\Renderer\Private\MegaLights\MegaLights.cpp:1316]
UnrealEditor_Renderer!FDeferredShadingSceneRenderer::Render() [D:\build++UE5\Sync\Engine\Source\Runtime\Renderer\Private\DeferredShadingRenderer.cpp:2845]
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]

6

I managed to workaround this issue: open another map, set it to “unlit”, now open bad map, that atlas crash will be gone for a little while

7

But if I click “Play” it will trigger this atlas bug no matter what. Disabling in project settings did not help. If anyone finds workaround for play mode, please let us know

8

For me it is indeed a particular level. I have other levels that will not crash when Megalights are enabled, but as soon as I open this level lit I get the crash above, beginnning with the light function atlas.

I don’t know why, as I don’t have any light functions in it, but there must be something in it that’s causing a crash. It’s a big complex level so I can’t really work out what.

9

Yes I have same experience so far. Guess I could decomposite my level and nail down the issue, but makes no sense anyway, its not like someEU engineer will come and fix it asap:D