protonscr

[SteamRT3] Custom command prefix in Launch Options won't work

steamclosed runtime
ValveSoftware/steam-for-linux#13008 · opened 2026-03-20 by Okunima · updated 2026-03-26 · 9 comments · github
3 matching comments, n / p to jump
OOkunima 2026-03-20 github

Your system information

  • Steam client version (build number or date): the latest beta build
  • Distribution (e.g. Ubuntu): CachyOS
  • Opted into Steam client beta?: [Yes/No] Yes
  • Have you checked for system updates?: [Yes/No] Yes
  • Steam Logs: [generate by running this command in a terminal tar -zcvf ~/Desktop/steam-logs.tar.gz ~/.steam/steam/logs]
  • GPU: Nvidia/Intel/AMD - AMD

Please describe your issue in as much detail as possible:

Describe what you expected should happen and what did happen. Please link any large code pastes as a Github Gist

If you have mangohud enabled as a launch option the games will not start. If you remove that launch option the games start without a problem

Steps for reproducing this issue:

  1. put mangohud %command% as launch option. The game will not start
  2. Remove mangohud %command% as launch option. The game will start
Ppollux78 2026-03-20 github

I have noticed also that removing mangohud from the launch command sometimes mangohud is still enabled when launching the game even tho there is no launch command to enable it and no i dont have it globally enabled either when checking goverlay.

Llucifertdark 2026-03-20 github

gamemoderun %command% is also preventing games from running for me.

Ssmcv 2026-03-20 github

put mangohud %command% as launch option. The game will not start

gamemoderun %command% is also preventing games from running for me.

This is a known issue, and will affect most custom commands in Launch Options. Tracked as steamrt/tasks#958 internally. A workaround is to not use the experimental version yet.

I have noticed also that removing mangohud from the launch command sometimes mangohud is still enabled when launching the game

I'm not sure what's going on there. I'd recommend waiting until the original issue reported here has been fixed, and then opening a separate issue report if this is still happening.

Ssmcv 2026-03-20 github

@kisak-valve, perhaps retitling this to something like [SteamRT3] Custom command prefix in Launch Options won't work (to broaden the scope to cover mangohud, gamemoderun, gamescope and all the rest) would avoid some duplicates?

OOkunima 2026-03-20 github

Done

VVladimirMrzv 2026-03-22 github

Same issue when trying start RE4 via gamescope for full screen

Llucifertdark 2026-03-22 github

@smcv I've gone back to the non experimental version for now as you suggested.

Ssmcv 2026-03-26 github

This was fixed in yesterday's beta client update 1774488570, so I think this issue can now be closed.

Unfortunately the changes that were made to fix this issue had the side-effect of making #13012 worse, but that regression is already tracked on #13012. A summary of the regression is: if your launch options look like FOO=bar %command% (for example MANGOHUD=1 %command or PROTON_LOG=1 %command%), then the game will not start. A workaround is to change your launch options so they look like env -- FOO=bar %command% instead.

Ssmcv 2026-03-26 github

@pollux78:

I have noticed also that removing mangohud from the launch command sometimes mangohud is still enabled when launching the game even tho there is no launch command to enable it and no i dont have it globally enabled either when checking goverlay.

If this is still happening for you in beta client 1774488570 or later, please open a separate issue with full details of how to reproduce the problem (the exact Launch Options that you used), the result you expected, and the actual result, together with logs (~/.steam/steam/logs/console_log.txt will be especially important).

Launch options

Launch lines