I decided to try moving the Proton Hotfix from my current disk to the disk the game is installed on and the game stopped launching altogether, but now the error appears:
...
Adding process 272280 for gameID 1304930
Adding process 272282 for gameID 1304930
wine: failed to open "c:\windows\system32\steam.exe": c0000135
pid 272278 != 272277, skipping destruction (fork without exec?)
Game Recording - game stopped [gameid=1304930]
Removing process 272282 for gameID 1304930
Removing process 272280 for gameID 1304930
...
Restarting the game the error partially disappeared:
Adding process 289147 for gameID 1304930
Adding process 289166 for gameID 1304930
Fossilize INFO: Overriding serialization path: "/home/u01eg/sbOne/SteamLibrary/steamapps/shadercache/1304930/fozpipelinesv6/steamapprun_pipeline_cache".
pid 289060 != 289059, skipping destruction (fork without exec?)
Game Recording - game stopped [gameid=1304930]
Removing process 289166 for gameID 1304930
Removing process 289147 for gameID 1304930
Restarting the third time the error disappeared altogether, but the game does not stop.
Might be an issue with the steam stub process. @kisak-valve , has there been any significant changes to the steam stub exe in protons 8 or 9? Perhaps there should be some logic to revert to the older (proton 7) stub methods in the event the steam exe fails.
Reports of this problem are starting to appear. Apparently, this doesn't just apply to UE4 games.
https://steamcommunity.com/app/221410/discussions/0/591771908358351828/
proton hotfixx1 2025-05
Games on UE4 run on Proton above version 7, but no image, the window is missing completely. No errors, hangs in processes, no notifications that the application is not responding and no problems with SELinux. Judging by the monitor only one processor core is being used. Fedora 42 with all updates. RADV. The problem appeared after switching from Fedora 40 to Fedora 41. I tried a lot of games, in particular Outlast Trials, Outlast 2, Scorn, Visage, etc. The problem is only with UE4 games. There are no problems with games on UE5.