r.Nanite.ForceEnableMeshes crashes Editor

Development Pipeline & Plugins
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1

Dear Support Team,

we have an issue with our project in the Editor. We recently added r.Nanite.ForceEnableMeshes=1 to the DefaultEngine.ini. We did this since the content is partially shared between projects but we do not use Nanite in all of the projects. That’s why we enforce Nanite in the project in which we want to have Nanite enabled. A build of the project did not show any problem so far. Ocassionally, the Editor crashes with an EXCEPTION_ACCESS_VIOLATION. It is not always in the same place. Some places where this happended

  • FDeferredShadingSceneRenderer::BindRayTracingMaterialPipeline (Engine\Source\Runtime\Renderer\Private\RayTracing\RayTracingMaterialHitShaders.cpp:1030)
  • FRendererModule::BeginRenderingViewFamilies’::`87’::<lambda_3>::operator()() (Engine\Source\Runtime\Renderer\Private\SceneRendering.cpp:4848)

We can constantly reproduce the EXCEPTION_ACCESS_VIOLATION when we try to open a Material Function asset from the Content Browser, also in a simple blueprint template project based on the first person shooter. This behaviour can be reproduced once r.Nanite.ForceEnableMeshes=1 was added to the DefaultGame.ini and a Material Function is double-clicked. How is r.Nanite.ForceEnableMeshes supposed to work? Did we miss a setting we need to enable as well or is this a known issue in UE 5.3?

Kind regards,

Jochen

2

Steps to Reproduce

  • Create blueprint template project based on first person template
  • In the DefaultEngine.ini add r.Nanite.ForceEnableMeshes=1 and restart the Editor
  • Create a Material Function in the Content Browser and save it
  • Simply double-click the Material Function in the Content Browser. The Editor will crash with an Access Violation error
3

Hello,

Thank you for reaching out.

I’ve been assigned this issue, and we will be looking into this crash for you.

4

Hello,

Thank you for reporting this issue. It is fixed in Unreal Engine 5.4, however, this specific crash was not tracked. The following CLs fixed a number of similar issues and crashes related to Materials, and they might be the solution to your crash as well. All are from //UE5/Main:

  • 30836040
  • 29401724
  • 30060552 and 31772526
  • 29386317

Please let us know if this helps.

5

Hello Stephen,

thank you for the clarification. We will evaluate if we can upgrade the project to UE 5.4. If we can not upgrade, we will try the mentioned CLs.

Kind regards,

Jochen

6

Hi,

yes, you can close it. We have enough information to go on. Thank you very much.

Kind regards,

Jochen

7

Hello,

Thank you for the reply.

Can we close your case? You can always re-open it if you have further questions about the same issue.