Steam/Proton game closes immediately with gamescope 3.16.23+, fixed by downgrading

[menchikatsu-sandwich]

Is there an existing issue for this?

• I have searched the existing issues

Are you using any gamescope patches or a forked version of gamescope?

• The issue occurs on upstream gamescope without any modifications

Current Behavior

After updating gamescope to 3.16.23+, launching a Steam Proton game with gamescope makes the game window appear briefly and then close immediately.

Gamescope itself works for simple applications. For example, this command works normally:

gamescope -- glxgears

However, launching the Steam/Proton game through gamescope closes immediately, even with the minimal launch option:

gamescope -- %command%

The Proton log shows Gamescope WSI being used, then Steam client connection errors:

[Gamescope WSI] Application info:
[Gamescope WSI] Executable name: explorer.exe

src/clientdll/steamclient.cpp (402) : Assertion Failed: ConnectToGlobalUser: Steam denied appID 3644924557
src/clientdll/steamclient.cpp (402) : Assertion Failed: ConnectToGlobalUser: Steam denied appID 3644924557

err:steamclient:steamclient_init_registry Failed to connect to Steam

info: DXVK: v2.7.1-591-g60978eb94c9ae51
info: Vulkan: Found vkGetInstanceProcAddr in winevulkan.dll

[Gamescope WSI] Executable name: xalia.exe

assert_20260604212515_3.dmp: Finished uploading minidump

Downgrading gamescope fixes the issue. After downgrading, the same game works again.

Steps To Reproduce

1. Update gamescope to 3.16.23+.
2. Launch a Steam Proton game with this launch option:
   gamescope -- %command%
   The gamescope/game window appears briefly.
   The game closes immediately.
   Run gamescope -- glxgears; this works normally.
   Downgrade gamescope.
   Launch the same game again with gamescope; it works.

Hardware information

Distro: CachyOS
CPU: Intel laptop CPU
GPU: NVIDIA GeForce RTX 4060 Laptop GPU
Driver Version: NVIDIA 610.43.02

Software information

Desktop environment: KDE Plasma
Session type: Wayland
Gamescope version with issue: gamescope version 3.16.23+ (gcc 15.2.1)
Gamescope launch command(s): 
      gamescope -- %command%
   Also tested:
      gamescope -f -- %command%, gamescope -f -W 2560 -H 1600 -w 2560 -h 1600 -r 120 -- gamemoderun %command%

Which gamescope backends have the issue you are reporting?

• Wayland (default for nested gamescope)
• DRM (default for embedded gamescope, i.e. gamescope-session)
• SDL
• OpenVR

Logging, screenshots, or anything else

gamescope-bug-report.tar.gz
gamescope-crash-tail.log
steam-15654831768735842304.log

[fantomfiter]

i also have this issue im on a rtx 2060 super wayland kde 6.7 fedora 43 nobara and i get it on minecraft via prism launcher and hollow knight via steam simple commands work but when i use gamescope -f -r 180 --backend sdl -w 1920 -h 720 -W 1920 -H 1080 -- %command% it crashes