Identify the failing layer
Steam Linux Runtime can put a game or Proton inside pressure-vessel isolation. A failed container setup is not the same as a Windows game executable crashing. Record whether the same game runs outside the affected runtime, which Steam Linux Runtime branch was chosen, and whether the game is a native build or uses Proton. Do not treat a generic missing-file message from inside the container as evidence that the file is absent on the host.
Collect discriminating evidence
Valve documents separate verbose runtime diagnostics. First inspect the current Steam Linux Runtime and its VERSION files where available; capture the exact error before a game window appears. If Steam itself is the Flatpak edition, distinguish Flatpak's outer sandbox from pressure-vessel's inner container. A log showing a runtime setup failure is more informative than blindly changing Vulkan ICD paths, replacing system libraries or installing a second Wine runner.
Compare safely and record limitations
Compare the same game, filesystem and hardware under one supported Steam compatibility selection at a time. Keep a record of branch choices and remove temporary verbose flags after collecting evidence. A historical workaround that switched an old Soldier or Sniper runtime is not a universal recommendation for current Steam releases. If a runtime downgrade changes the outcome, report both version identifiers and the isolated difference rather than calling the game itself fixed.
Gather evidence before changing the system
Run one command at a time in the relevant host or game environment. Read its requirements and interpretation first. The website displays commands and never runs them.
Read-only observation
steam --versionRequirements: Run in the relevant host/session; compare with the actual game environment and redact private paths before sharing.
Shows a client-reported build only; does not identify the container revision.
Read-only observation
env | grep -E '^(STEAM|PRESSURE_VESSEL|FLATPAK)'Requirements: Run in the relevant host/session; compare with the actual game environment and redact private paths before sharing.
Check inherited runtime overrides without exporting credentials or paths publicly.
A controlled test with a way back
Save launch options; rerun Steam once with STEAM_LINUX_RUNTIME_VERBOSE=1 from a terminal and reproduce one startup.
Rollback: Remove the environment override and restore the selected compatibility tool.
What this test cannot establish: Verbose output can contain personal paths and does not identify a defective GPU.
Sources and scope
This editorial review uses primary project and distribution references. It does not establish that a fix has been reproduced on your hardware. Installed versions, the game runtime and the selected graphics API can change the result.
- Steam Linux Runtime bug-report guidance
Valve separates pressure-vessel logging from game-level failures.
- Valve Proton runtime and logging
Valve documents per-game Proton logging and runtime options.