Crash save/apply Material Layer in RenderGraphValidation.cpp in UE5.5.4

Development Asset Creation
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1

Hi.

Since we upgraded form 5.4 to 5.5 we got a crash while apply/save some materials that wasn’t crashing in 5.4. It’s a material layer and from what I can see in the callstack it seems to be related to preview and Virtual Texture? So I’ve disabled all preview and even output node preview and crash at least +90% of the time. I’ve try in Vanilla 5.5 … any idea what would cause that from the callstack?

cheers

2

Hi,

The crash appears to be caused by a mismatch in resource access modes for the VirtualTexture_PageTable. Specifically, the error indicates that the resource is in an external access mode and is valid for access with states like SRVCompute, SRVGraphicsPixel, and SRVGraphicsNonPixel. However, it is being used in a rendering pass (PageTableUpdate) with RTV (Render Target View) access, which is not compatible with its current access mode.

I’ve been digging a bit further and found a thread on the Unreal dev forums reporting a crash which looks very similar to this one (second crash in first post). According to that thread, the crash no longer occurs with 5.5.4. Unfortunately I could not find the specific commit that fixed it, so I’m not entirely sure what is causing the crash.

If your project is not on 5.5.4 yet, could you try upgrading to it?

Let me know if that works, if not we can investigate this further.

Thanks,

Sam

3

We’re already on 5.5.4.

in the meantime I’ve deleted all folder with shaders in the name in saved folder (game and engine) and no crash so far … I would say to close the post and if it happen again I’ll reopen it.

4

Just crash … do don’t close it …

5

Hi,

thanks for getting back. Can you try the other suggestion in the thread I linked (moving the texture samplers to functions)? This might be a workaround in the meantime until a fix has been released.

If that doesn’t work, could you please add steps to reproduce the crash from a blank project or attach a minimal project?

Thanks,

Sam

6

Read it too fast and saw that if the unique texture sample I have is not visible it will not crash O_o. So yeah if I move it to a function it will not be visible and not crash. I’ve try multiple time in vanilla 5.5.4 and it doesn’t crash

nothing really complicated that is plugged in that texture it’s a 4x4 default texture that is virtual … I even try to make it 128x128 but same thing happened. Even try to delete the texture sample and create a new one. Unplugged UVs and still crash and for a last test I’ve put a standard texture instead of virtual and it doesn’t crash.

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7

Hi,

good to hear that workaround solves the crash. I would like to file a bug report with Epic for this issue but have not been able to reproduce it in Unreal Engine 5.5.4 (I have replicated your graph, but didn’t see any crashes when applying/saving the material or unplugging the UVs). Would you be able to attach a minimal project with this material?

Thanks