Proton-cachyos not working on Rog Ally

Issues & Assistance
1

Hello. I just installed CachyOS on my ROG Ally. I downloaded the latest iso and did a clean install to the SSD. After installing, I logged in with my Steam account as usual, then went into the Desktop. I installed the Gaming Packages from the hello screen. It installed all the usual stuff. Then I added some games to Lutris, selecting the proton-cachyos runner.

So far, this is exactly the same steps I did on my gaming PC, only difference is that on my PC I installed the desktop version, on Ally I installed the handheld version.

On my PC, without doing anything else, my games work just fine on Lutris. On the Rog Ally, I get this

2025-07-14 10:38:28,804: Starting Lutris 0.5.19
2025-07-14 10:38:28,830: "card0" is AMD Radeon Graphics (1002:15bf 1043:17f3 amdgpu) Driver 25.1.5
Fontconfig warning: using without calling FcInit()
2025-07-14 10:38:30,027: No valid prefix detected in /home/deck/Games/xxxx, creating one...
2025-07-14 10:38:30,028: Creating a win64 prefix in /home/deck/Games/xxxx
2025-07-14 10:38:30,028: Winepath: /usr/share/steam/compatibilitytools.d/proton-cachyos/files/bin/wine
lutris-wrapper: /home/deck/.local/share/lutris/runtime/umu/umu-run
Started initial process 8603 from /home/deck/.local/share/lutris/runtime/umu/umu-run createprefix
Start monitoring process.
INFO: umu-launcher version 1.2.9 (3.13.5 (main, Jun 21 2025, 15:00:45) [GCC 15.1.1 20250425])
ERROR: Failed to match '/usr/share/steam/compatibilitytools.d/proton-cachyos' with a container runtime
Traceback (most recent call last):
  File "/home/deck/.local/share/lutris/runtime/umu/umu-run/__main__.py", line 95, in <module>
    sys.exit(main())
             ~~~~^^
  File "/home/deck/.local/share/lutris/runtime/umu/umu-run/__main__.py", line 90, in main
    return umu_run(args)
  File "/home/deck/.local/share/lutris/runtime/umu/umu-run/umu/umu_run.py", line 822, in umu_run
    raise ValueError(err)
ValueError: Failed to match '/usr/share/steam/compatibilitytools.d/proton-cachyos' with a container runtime
Monitored process exited.
Initial process has exited (return code: 0)
All processes have quit
Exit with return code 0

From what I can tell, it does not create a prefix in the wineprefix folder that I set up, then stops immediately with the messages you can see above. Error is literally the same with any game or program I try to run.

The problem is only with proton-cachyos, not with wine-ge (default). The games work in wine-ge, it creates a prefix as usual and then runs the windows exe.

I literally have not made any change to the installed OS, it has been clean installed just a few minutes ago.

Please help. Thanks in advance.

2

afaik proton-cachy is only the compatibility layer that works on steam. but i could be wrong there.
you can try stagging on lutris. thats what i do. its the cachy-wine that should have the same configuration as cachy-proton.

i just tried to start a game with proton-cachy on lutris and it doesnt start too.
and im on the desktop version so i think it got nothing to do with it.
it worked that way a while ago but with some systemupdate it changed as far as i remember.

3

Ok I fixed it. Long story short, I had to install umu-launcher (whatever it is, I don’t even know).

sudo pacman -S cachyos/umu-launcher

Then it will work in Lutris just fine.

I don’t recall doing this on my desktop, but I recall I installed Lutris BEFORE installing the gaming packages, and when I installed Lutris it allowed me to pick a bunch of optional libraries for it including this umu-launcher thing. I know for sure that I selected all of them (since I didn’t knew what any of them actually did except maybe two of them). After that I installed the gaming package and everything worked just fine.