UE4.9 Preview 4 Insta-crashes on launch with -D3D12 parameter

As requested by OriginalAdric on Reddit, I am cross posting my crash-on-start support request. Unreal Engine 4.9 Preview 4 crashes immediately on launch, sometimes actually displaying the editor, and sometimes crashing before it even starts, when the -D3D12 parameter is enabled via a shortcut.

I’ve tried rebuilding the engine and have double and triple checked that my GPU drivers are up to date, as well as all updates are installed in Windows. So far nothing has seemed to help and the issue still occurs. Even making a completely new project doesn’t help. Launching as admin doesn’t help. Etc. etc.

DXDiag - Paste.ee

Latest Crash Log - Paste.ee

Hi Brandonmule,

Do you get a window appearing asking you to send in your crash report? If so, could you copy the callstack from that window and send it to me? That way I can look it up in our system and see if this exact crash has already been reported.


Not sure if this is what you needed, but this is all that I get from the crash window.

Hi Brandonsmule,

We now have an active investigation going for this issue. It is entered as UE-20622 in our system.


Awesome. Thank you very much.

Is there any update on this? The original issue was in 4.9p4, the official 4.9.0 launch, and tonight I updated to 4.9.2 and found the exact issue is still present. =/


I find a solution for this crash.If you have game booster or gaming app for graphic cards just close it and then try again it worked for me.Sorry for my bad english i hope it will be work for you.

Hmm… I don’t have anything of the sort running or even installed. The closest thing would probably be GeForce Experience/ShadowPlay running in the background.

I think that I may have found a fix as well, though I’m not sure exactly what helped.

  1. Adding UE4 to “Manage 3D Settings” in the Nvidia Control Panel and setting “CUDA - GPUs” to a single GPU instead of “use global setting” in an SLI rig.
  2. Enabling “Debug Mode” under “Help” in the Nvidia Control Panel

My best guess would be the enabling Debug Mode in the NVCPL since (from my understanding at least) it disables any overclock that you’ve set on your GPU(s) and reverts them back to the (Nvidia) factory stock clock speed. I am running custom firmware on my GPUs which may have had in impact on compatibility with DX12 and UE4.

It didn’t crash in the 2 hours that I was working in the editor, where it used to crash seconds after launch. Seems fixed(?) for now, at least.

Hi Brandonsmule,

There is no update right now. A fix is yet to be found, but it is assigned to and being worked on by an engineer.