UE4 Fatal error or black screen when launching (linux)

[old486whizz]

Heya guys,

Just thought I'd post in here since my steam on Linux using the default proton (or latest, or 8.0.2) produces the following errors for me.
It seems UE4 and RMI related - but I was eventually able to get it fixed.

When trying to start normally, it comes up with a "UE4 Fatal Error" pop up message box with no further details.
Searching around, I found the launch option "PROTON_USE_WINED3D=1 %command%" - which allowed me to get a black window - but nothing else.. So that was a step forwards.
I also found a launch option of "%command% -opengl" - which had UE4 coming back saying the RMI of opengl was no longer supported.
... So, I went on a search to try and find an explicit vulkan option (-opengl4 didn't work, -opengl came back as unsupported.... and the wined3d variable must be making it do something with DirectX)..
I didn't find anything really - however, I did find a "-dx11" and "-dx12" option.
... So I decided to use those instead:
"%command% -dx11" = black screen again
"%command% -dx12" = a working game!!

No idea why, but the translation from DX11 (into I hope vulkan) is not working correctly, while the DX12 is...

I write this post in the hopes that if anyone else is experiencing the same issues, that they may stumble across this.

For any debugging purposes:
intel CPU / intel GPU / 16G RAM / Linux (Fedora 38) / KDE / Wayland

--
old486whizz

[Vondor]

Dont know how to solve your Problem, but I can tell it works well on SteamDeck (Arch). But I had to choose Proton 8.0.2.

[TheMa dArtist]

I tried this and it still doesnt work! On proton 8 it doesnt launch and on proton 7 it still gives the fatal error

[child of glue]

Have you installed proton glorious eggroll (G.E.) builds? they seem the most stable in my experience.