GPU Crash / PageFault (MMU Fault) in Lumen HWRT and VSM on Dynamic Skeletal Mesh Despawn & World Streaming

Development Rendering
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We are encountering an intermittent GPU crash (resulting in DXGI_ERROR_DEVICE_HUNG)

in our packaged builds on Unreal Engine 5.7.4. The crash primarily occurs during two specific gameplay events:

  • Spawning and despawning vehicle actors (Skeletal Meshes with attached components) in quick succession.
  • Traversing our World Partition map (with or without the vehicle)

The crash seems to occurs at different location depending on the frame state:

  • Lumen HWRT: Failing inside LumenScreenProbeGatherHardwareRayTracingCS or LumenRadianceCacheHardwareRayTracingCS
  • Virtual Shadow Maps: Failing inside RenderVirtualShadowMaps

We resolved the crash by completely disabling ray-tracing attributes on our vehicle actors:

  • Disabling “Visible in Raytracing” on all meshes inside our vehicle components (both static and skeletal).
  • Disabling Affect Ray Tracing Reflections & Affect Ray Tracing Global Illumination on all vehicle-attached light components.

While this workaround seems to prevent the crash, we would like to confirm if this is an actual correct fix, if it is an engine bug, or if we just fixed part of the issue by disabling raytracing on the vehilcle but it could still occur.

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Hello,

This doesn’t sound like a known issue, but it could be a resource lifetime issue or possibly related to the driver running out of shader heap space when it is compiling RT shaders for the vehicles and components.

If you have a repro case that you can share with us, that would help us investigate, but if not, you can also see if r.RayTracing.UseReferenceBasedResidency=0 has any affect.

Please attach a log and Aftermath dump from an example crash which may provide additional useful information.

If no Aftermath dump is generated it could be related to a possible driver shader heap issue and you could see if increasing your shader heap locally resolves the issue [Content removed]

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