DirectX12 GPU related Crash

Development Getting Started & Setup
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1

With 5.5.4 and using a AMD GPU - when opening a DataTable and moving the Editor window the following error and crash happens

Assertion failed: TryAllocateInternal(InSize, AllocationAlignment, AllocationResourceType, AllocationData) [File:D:\build++UE5\Sync\Engine\Source\Runtime\D3D12RHI\Private\D3D12PoolAllocator.cpp] [Line: 375]

Ensure condition failed: InSizeAfterCompaction > 0 [File:D:\build++UE5\Sync\Engine\Source\Runtime\D3D12RHI\Private\D3D12RayTracing.cpp] [Line: 3456] LogOutputDevice: Error: Compacted acceleration structure size is expected to be non-zero. This error suggests that GPU readback synchronization is broken.

There are two solutions

Fixed by setting DirectX11 instead of DirectX12 in the DefaultGame.ini

[/Script/WindowsTargetPlatform.WindowsTargetSettings]
DefaultGraphicsRHI=DefaultGraphicsRHI_DX11

Another fix is to keep using DirectX12, but set the Editor window not to fullscreen, the window can be scaled as large as needed, the crash no longer occurs.

2

Hi @unit23
Let’s see…

The error you’re encountering in Unreal Engine (UE5) with an AMD GPU and DirectX 12 (DX12) occurs due to issues with GPU memory allocation and synchronization when moving the Editor window. There are two potential solutions:

Switch to DirectX 11: Change the graphics API in your DefaultGame.ini to use DX11 instead of DX12, which avoids the synchronization problem

[/Script/WindowsTargetPlatform.WindowsTargetSettings]
DefaultGraphicsRHI=DefaultGraphicsRHI_DX11

Avoid fullscreen mode in DirectX 12: Keep using DX12 but ensure the Editor window is not in fullscreen mode, as the crash doesn’t occur when the window is resized instead of fullscreen