Unreal 5.4.4 crashes after load of level

General Feedback & Requests
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1

I have a world-partition project, copied from 5.3 to 5.4.3 that has some quirks in display in one level ( Viewport becomes unusable after moving cursor - General / Feedback & Requests - Epic Developer Community Forums (unrealengine.com) but no other problems. I usually have one region opened , done quite a lot of edits but it all worked.
However, after the update to Unreal 5.4.4, opening that same project caused a crash of UnrealEditor with the message:

Error: Assertion failed: ScratchBufferRequiredSize + ScratchBufferOffset <= ScratchBufferSize [File:D:\build\++UE5\Sync\Engine\Source\Runtime\D3D12RHI\Private\D3D12RayTracing.cpp] [Line: 3934] 
[2024.09.19-19.03.32:963][691]LogWindows: Error: BLAS scratch buffer size is 10081422919936 bytes with offset 662558289920 (1349888 bytes available), but the build requires 1354496 bytes.

No change was made to the project!

I have the original 5.3.2 version at hand so I re-did the migration from 5.3.2 to 5.4.4, opened that project and again, after the project was loaded, Unreal crashed again:

> Assertion failed: ScratchBufferRequiredSize + ScratchBufferOffset <= ScratchBufferSize [File:D:\build\++UE5\Sync\Engine\Source\Runtime\D3D12RHI\Private\D3D12RayTracing.cpp] [Line: 3934] 
> [2024.09.19-20.16.08:673][717]LogWindows: Error: BLAS scratch buffer size is 6425849810432 bytes with offset 395715042560 (2314988056832 bytes available), but the build requires 1298944 bytes.

The end of the logfile is (apart from the counters) the same:

2024.09.19-19.03.31:425][691]LogWindows: Error: appError called: Assertion failed: ScratchBufferRequiredSize + ScratchBufferOffset <= ScratchBufferSize [File:D:\build++UE5\Sync\Engine\Source\Runtime\D3D12RHI\Private\D3D12RayTracing.cpp] [Line: 3934]
BLAS scratch buffer size is 10081422919936 bytes with offset 662558289920 (1349888 bytes available), but the build requires 1354496 bytes.

[2024.09.19-19.03.31:427][691]LogWindows: Windows GetLastError: The operation completed successfully. (0)
[2024.09.19-19.03.32:962][691]LogRHI: Error: Breadcrumbs 'RHIThread'

[2024.09.19-19.03.32:962][691]LogThreadingWindows: Error: Runnable thread RHIThread crashed.
[2024.09.19-19.03.32:963][691]LogWindows: Error: === Critical error: ===
[2024.09.19-19.03.32:963][691]LogWindows: Error: 
[2024.09.19-19.03.32:963][691]LogWindows: Error: Assertion failed: ScratchBufferRequiredSize + ScratchBufferOffset <= ScratchBufferSize [File:D:\build\++UE5\Sync\Engine\Source\Runtime\D3D12RHI\Private\D3D12RayTracing.cpp] [Line: 3934] 
[2024.09.19-19.03.32:963][691]LogWindows: Error: BLAS scratch buffer size is 10081422919936 bytes with offset 662558289920 (1349888 bytes available), but the build requires 1354496 bytes. 
[2024.09.19-19.03.32:963][691]LogWindows: Error: 
[2024.09.19-19.03.32:963][691]LogWindows: Error: 
[2024.09.19-19.03.32:963][691]LogWindows: Error: [Callstack] 0x00007ffe571ccfa7 UnrealEditor-D3D12RHI.dll!UnknownFunction []
[2024.09.19-19.03.32:963][691]LogWindows: Error: [Callstack] 0x00007ffee101f00d UnrealEditor-RHI.dll!UnknownFunction []
[2024.09.19-19.03.32:963][691]LogWindows: Error: [Callstack] 0x00007ffee102266f UnrealEditor-RHI.dll!UnknownFunction []
[2024.09.19-19.03.32:963][691]LogWindows: Error: [Callstack] 0x00007ffee10203b6 UnrealEditor-RHI.dll!UnknownFunction []
[2024.09.19-19.03.32:963][691]LogWindows: Error: [Callstack] 0x00007ffee100b4db UnrealEditor-RHI.dll!UnknownFunction []
[2024.09.19-19.03.32:963][691]LogWindows: Error: [Callstack] 0x00007ffee102606f UnrealEditor-RHI.dll!UnknownFunction []
[2024.09.19-19.03.32:963][691]LogWindows: Error: [Callstack] 0x00007ffe99eeb88a UnrealEditor-Core.dll!UnknownFunction []
[2024.09.19-19.03.32:963][691]LogWindows: Error: [Callstack] 0x00007ffe99eebf2e UnrealEditor-Core.dll!UnknownFunction []
[2024.09.19-19.03.32:963][691]LogWindows: Error: [Callstack] 0x00007ffec4a0641d UnrealEditor-RenderCore.dll!UnknownFunction []
[2024.09.19-19.03.32:963][691]LogWindows: Error: [Callstack] 0x00007ffe9a52c93d UnrealEditor-Core.dll!UnknownFunction []
[2024.09.19-19.03.32:963][691]LogWindows: Error: [Callstack] 0x00007ffe9a5202b7 UnrealEditor-Core.dll!UnknownFunction []
[2024.09.19-19.03.32:963][691]LogWindows: Error: [Callstack] 0x00007fff1d18257d KERNEL32.DLL!UnknownFunction []
[2024.09.19-19.03.32:963][691]LogWindows: Error: 
[2024.09.19-19.03.32:963][691]LogWindows: Error: Crash in runnable thread RHIThread
[2024.09.19-19.03.32:989][691]LogExit: Executing StaticShutdownAfterError
[2024.09.19-19.03.33:320][691]LogWindows: FPlatformMisc::RequestExit(1, FRunnableThreadWin::GuardedRun.ExceptionHandler)
[2024.09.19-19.03.33:320][691]LogWindows: FPlatformMisc::RequestExitWithStatus(1, 3, FRunnableThreadWin::GuardedRun.ExceptionHandler)
[2024.09.19-19.03.33:320][691]LogCore: Engine exit requested (reason: Win RequestExit)


Biggest problem now is that I cannot undo the latest update and revert to 5.4.3 - that I could use.
2

I added more information on this issue in the related post
Undo update - Development / Platform & Builds - Epic Developer Community Forums (unrealengine.com)

I found a workaround, described in that post.

UPDATE:
If I open the level with one or two regions loaded (including the generated PCG’s) there is nothing wrong - it takes about 30 mintes (25 or so at 84%). I can load other regions so I have all 4 regions loaded but run into the unusable viewport. Closed the project yesterday with all regions loaded and all PCG’s generated.
Today I opened the level again and again, Unreal crashed. After restart in the default (standard) level I looked at the folder that holds my spline-based PCG’s and found that all my data-assets are no longer covered by their icon:

image
image3134×1049 175 KB

This is the log of the latest crash:
Oasis-backup-2024.10.02-13.46.13.log (316.7 KB)
but when I rename such a file, the class is corrected.

My suspicion is that the spline- and data-asset based PCG’s are key to this problem, because if I remove them from my project, I can load all 4 regions without a problem. A few is not a problem but I have about 8 in each regions, each covering a large area.

I will have to postpone further work on this project, this blocks me completely; I need all four regions loaded for the next step I had in mind, until this is solved.