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

[Hi-Im-Ghost]

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):

StreamlineLibraryDLSSG::SetDLSSGMode(Off)

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

UGameUserSettings::SetFullscreenMode(...)

UGameUserSettings::SetScreenResolution(...)

UGameUserSettings::ApplySettings(true)

Optional delay / tick

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!

[Adriwin06]

Hey, sorry for the delay.
I really didn't have the time to work on anything in the past few months (and probably won't really have the time for a few more), so I can't really say what the problem is here.
I did make some progress on the plugin version, but not that much, because everything needs to be redone with the new workflow, and I don't have the time to do it alone.
If you or anyone else who has some good Unreal Engine knowledge is interested in helping me, add me on Discord (#adriwin78), so we can finally update this.