Lumen render crashes

I’m getting crashes mid render on some Lumen renders, about 400 frames, spatial 32, temporal 4:

Unhandled Exception: EXCEPTION_ACCESS_VIOLATION 0x00007ff99166f800

UnrealEditor_D3D12RHI
UnrealEditor_D3D12RHI
UnrealEditor_D3D12RHI
UnrealEditor_D3D12RHI
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
kernel32
ntdll

I’ve got some metahumans in the scene, with baked animations, Lumen for lighting, UE 5.1.1, and I can’t seem to get thru some of these renders without these errors causing crashes.
Running on a Intel i9, RTX 3090 with 128GB ram

Hi @Nino_Mancuso

I also had these redundant crashes especially on Pathtracing at the beginning, then I quickly realized that any rendering (Lumen or normal) on DirectX12 makes my Unreal Engine crash on my computer.

The UnrealEditor_D3D12RHI error comes from DirectX12, try to switch to DirectX11 in your Unreal settings (Project settings → Windows → Default RHI to DirectX11).
Normally you should be able to render like this.

Before you answer me, you do lose RayTracing but this is the only “rational” solution I found for this problem, welcome to Unreal 5.1 (I didn’t have this problem in 5.0.3).

Flavien

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