I also have issue relate to Proton experimental and hostfix. I not sure that it related but i cannot open new issue so i drop here screenshot. I suspect that proton use wine predefined as WIndows XP, which is incompatible to directx11.

this issue appeared after 30 Apr. Before I was able play without issue.

I would like to mention that I also have this issue, and provide a little more information. The problem seems to be most likely to occur with Unreal Engine games, at least for me. Coral Island, Void Crew, and R.E.P.O. are all non-functional with the error message shown above about DirectX unless run with Proton 8. I have not had time to check further titles.

I tried running different games and made a new archive with logs:
steam-logs-2.tar.gz
Something started, something didn't.

I would like to mention that I also have this issue, and provide a little more information. The problem seems to be most likely to occur with Unreal Engine games, at least for me. Coral Island, Void Crew, and R.E.P.O. are all non-functional with the error message shown above about DirectX unless run with Proton 8. I have not had time to check further titles.

I didn't have any problems with the UE game (robocop rogue city). There were problems with games on other unknown engines and with the game on unity.
Specifically, which version of proton did you manage to launch the games with?

I also have issue relate to Proton experimental and hostfix. I not sure that it related but i cannot open new issue so i drop here screenshot. I suspect that proton use wine predefined as WIndows XP, which is incompatible to directx11.

this issue appeared after 30 Apr. Before I was able play without issue.

As far as I know, steam uses a modified valve version of wine, and it's called proton. They're working on it.
Have you tried running your game with forced compatibility mode?
For example with Proton 8.0-5? Alternatively, use the ProtonUp-Qt utility to add other versions of proton, for example, try GE-Proton8-32.

Kingdom Come Deliverance 2 (CryEngine) worked Thursday, black-screen or only splash screen Friday. Tried Proton Experimental, GE, 9, 8 - none seem to work - most failing either at the splash screen or before the Warhorse video logo at a black fullscreen with game cursor. If I clear all caches, I can get to the EULA screen with game background sounds, but hitting "E" to agree to terms, the game locks and sounds stop.

Debian Trixie
Gnome / Wayland
AMD Ryzen 9 7950X3D
AMD Radeon RX 7900 XTX
Proton 9.0 Build ID: 17797868

Edit: my issue was with Mesa 25.0.4. Downgrading to 25.0.3 solved the issue for me.
Edit: Mesa 25.0.5 has the same issue, so sticking with 25.0.3 a while longer.

I would like to mention that I also have this issue, and provide a little more information. The problem seems to be most likely to occur with Unreal Engine games, at least for me. Coral Island, Void Crew, and R.E.P.O. are all non-functional with the error message shown above about DirectX unless run with Proton 8. I have not had time to check further titles.

I didn't have any problems with the UE game (robocop rogue city). There were problems with games on other unknown engines and with the game on unity. Specifically, which version of proton did you manage to launch the games with?

I went with Proton 8.0-5 via the "Force the use of a specific Steam Play compatibility tool" setting

Failed to initialize graphics.
Make sure you have DirectX 11 installed, have up to date
drivers for your graphics card and have not disabled
3D acceleration in display settings.
InitializeEngineGraphics failed

I also have this issue with Proton Experimental on multiple games using Unity Engine. Using Proton 9 works OK. I am on Debian Sid with GTX 3060 TI and 535.216.03 drivers.

+1 Latest updates are indeed a bit wonky. Currently Proton Experimental and 10 beta makes Falcon BMS crash when running in SteamVR mode (no-VR mode seem to be fine) It sued to work with Experimental last week or so.
I'll try to roll back to 9.0 and see, but it may take moment as changing Proton runtime breaks required registry entries, so complete reinstall is needed,

I also have issue relate to Proton experimental and hostfix. I not sure that it related but i cannot open new issue so i drop here screenshot. I suspect that proton use wine predefined as WIndows XP, which is incompatible to directx11.
this issue appeared after 30 Apr. Before I was able play without issue.

As far as I know, steam uses a modified valve version of wine, and it's called proton. They're working on it. Have you tried running your game with forced compatibility mode? For example with Proton 8.0-5? Alternatively, use the ProtonUp-Qt utility to add other versions of proton, for example, try GE-Proton8-32.

Proton8-32 not helped but Proton10-beta correctly started game and even allow play good. but it have other issue, when I switch from fullscreen and then return game window resizes to very small(256x240) and impossible to maximize.
I not know is it proton10-beta issue or not but anyway it's better then nothing.

Hi everyone! If you're using an NVIDIA GPU, please check this to see if it's related to the issue.

I am using an NVIDIA GPU, however the first thing I did was update my drivers, just to make sure that wasn't the issue...

I checked it out. As of May 17, quite a large part of the games from my library that once worked on proton experimental have not been launched with it since the beginning of May. Even the "sid meier's civilization V" doesn't start anymore.

I'm also having this issue with Sonic X Shadow Generations and Sonic Frontiers.

Protontricks was closed due to the following error:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/protontricks/cli/util.py", line 149, in wrapper
    return cli_func(self, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/protontricks/cli/main.py", line 274, in main
    proton_app = find_proton_app(
                 ^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/protontricks/steam.py", line 821, in find_proton_app
    tool_app = find_steam_compat_tool_app(
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/protontricks/steam.py", line 610, in find_steam_compat_tool_app
    appinfo_sections = [
                       ^
  File "/usr/lib/python3/dist-packages/protontricks/steam.py", line 540, in iter_appinfo_sections
    raise SyntaxError("Invalid file magic number")
SyntaxError: Invalid file magic number


=============

Please include this entire error message when making a bug report.
Log messages:

Found Steam directory at /home/dee/.local/share/Steam
Using default Steam Runtime at /home/dee/.local/share/Steam/ubuntu12_32/steam-runtime
WINETRICKS environment variable is not available. Searching from $PATH.
Found 1 Steam library folders
Currently logged-in Steam user: dekuelegy
Found 0 Steam shortcuts running using Steam compatibility tools
Using 'zenity' as GUI provider

I'm on an AMD Ryzen 5 9600X, 6 cores, 3.9 Ghz & Asus GeForce RTX 3060 Phoenix 12G.