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winebus fails to start on Proton 11 — "Failed loading SDL3 library" (sdl2-compat/SDL3), breaks all controllers

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ValveSoftware/Proton#9939 · opened 2026-07-02 by MoutonSanglant · updated 2026-08-15 · 2 comments · github
MMoutonSanglant 2026-07-02 github

I was frustrated to not be able to play with new GStreamer and controllers, so...

Summary: On Proton 11 (Beta), winebus crashes at init with Failed loading SDL3 library + a Wine assertion, breaking all in-game controller input. Works on Proton 9.0-4 / 10.0-4. Reproducible across multiple games; the controller is seen by Steam and the OS, ignored only inside games.

Tested on Clair-Obscur : Expedition 33, Tunic, ABZU

System: Arch Linux, kernel 6.18 LTS, AMD RX 7800 XT (RADV/Mesa 26.1), Steam Flatpak + Steam Linux Runtime (sniper). Controllers: Xbox One (xpad), DualShock 4 (hid-playstation).

By version (same prefix/hardware): 9.0-4 & 10.0-4 → work; 11.0 → dead, Steam Input on or off.

Root cause (winebus log): winebus.sys loads as a module, then the SDL backend fails — Failed loading SDL3 library, immediately followed by EXCEPTION_WINE_ASSERTION in libc, a corrupted stack (Exception frame is not in stack limits), and winebus failed to start: 1053. The bus never starts, so no controller is enumerated. winebus targets the SDL2 API; in sniper, SDL2 is sdl2-compat loading SDL3 underneath, and the crash originates in that sdl2-compat/SDL3 chain — likely related to the containerized SDL3/sdl2-compat reports.

Workaround (fully restores controllers on 11):

  1. Prefix: HKLM\System\CurrentControlSet\Services\winebus → Enable SDL=dword:0 — skips the crashing SDL backend, winebus starts via udev.
  2. Load the uinput module.
  3. Enable Steam Input (forced On).

Steam Input's virtual X360 pad is then created via uinput and picked up by winebus's evdev backend (the commit HACK: winebus: Use evdev backend for the Steam Input virtual controllers path lead me there), bypassing SDL entirely. Without uinput, no virtual pad is created and Steam Input silently does nothing.

Steam Flatpak note: On my OS, controllers were invisible to Steam until adding host udev rules (ValveSoftware/steam-devices) + flatpak override --filesystem=/run/udev/data:ro com.valvesoftware.Steam — a separate prerequisite from the crash above.

Attachments:

  • steam-1903340-sdl_enabled: Logs with SDL enabled
  • steam-1903340-sdl_disabled: Logs with SDL disabled
  • steam-1903340-fixed: Logs with SDL disabled + uinput + SteamInput

Related issue (but it's Proton 9/10):

Zzufica1337-del 2026-07-13 github

Hello sir how do i fix this issue on gamenative ,is there a way to add this line in the environment section of the container settings ?

Thank you

Ddeadbeef7 2026-08-15 github

My psvita controller through vitapad isn't working on ge 11 nor experimental nor valve 11 but proton em 10 works for some reason

Proton versions

Upstream links