UE 5.6 DX12 crash on ApplySettings / ResizeBuffers when NVIDIA DLSS Frame Generation (Streamline DLSSG) is enabled (DXGI error 0x8000000A / E_PENDING)

Gaming and Visualization Technologies General Topics & Other SDKs
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Hi,

I’m hitting a reproducible crash in Unreal Engine 5.6 (D3D12) when applying video settings while NVIDIA DLSS Frame Generation (Streamline DLSSG plugin) is enabled. From an in-game UI (UMG/CommonUI), I call GameUserSettings to apply resolution and window mode changes (and then save). This crashes only when DLSS Frame Generation is enabled. I tried to get around the problem by turning off the generator during changes and then turning it back on, but I was unsuccessful.
Blueprint flow (simplified):

  1. StreamlineLibraryDLSSG::SetDLSSGMode(Off)

  2. (Tried) FlushRenderingCommands() / FRenderCommandFence (BlueprintCallable C++ helper)

  3. UGameUserSettings::SetFullscreenMode(...)

  4. UGameUserSettings::SetScreenResolution(...)

  5. UGameUserSettings::ApplySettings(true)

  6. Optional delay / tick

  7. Restore FG mode: StreamlineLibraryDLSSG::SetDLSSGMode(PreviousMode)

I also tried:

  • Waiting (Delay 0.2 / next tick)

  • Borderless / Windowed / Exclusive Fullscreen (doesn’t matter)

  • Disabling HDR / changing tearing settings (no change)

  • Using only API calls (no CVars)

  • Render-thread flush + fence before ApplySettings (no change)

The crash:

LogD3D12RHI: Error: SwapChain1->ResizeBuffers(NumBackBuffers, SizeX, SizeY, UE::DXGIUtilities::GetSwapChainFormat(PixelFormat), SwapChainFlags) failed
...WindowsD3D12Viewport.cpp:310
with error 8000000A
Viewport=..., Num=3, Size=(1024,768), PF=18, DXGIFormat=0x18, Fullscreen=1, AllowTearing=1

Fatal error: ... D3D12Util.cpp [Line: 1015]
SwapChain1->ResizeBuffers(...) failed ... with error 8000000A

Script stack shows it happens when my UI calls “SafeApplyVideoSettings” → ApplySettings.

Is this a known issue/limitation in UE 5.6 with Streamline DLSS Frame Generation + DX12 swapchain resizing?
What is the recommended way to safely apply resolution/window mode changes when DLSS-G is enabled?
Thanks!

2

Hi. Try adding this command to your DefaultEngine.ini

[SystemSettingsEditor]
r.Streamline.Load.DLSSG=0

This prevents DLSS Frame Generation from loading in the editor process, so Streamline never installs its swapchain provider and can’t crash on ResizeBuffers. FG in the shipped product or standalone is unaffected.