System information

• Steam client version: 1782866176 (built Jun 24 2026 23:24:37)
• Distribution: Linux Mint 22.3 (Zena), Ubuntu 24.04 base
• Kernel: 6.17.0-35-generic
• GPU / driver: NVIDIA GeForce RTX 3060, driver 580.159.03 (open kernel module)
• Steam client beta: No
• Proton: Proton Experimental (also affects multiple Proton titles)
• Controller: PlayStation DualSense (serial FXA9954901415, logged as controller_triton)

Issue description

After configuring trackpad mapping on a DualSense for the first time (via Steam Input), game launches began hanging. Steam shows the game as launching, but Proton/game processes often never start. Clicking Stop can take several minutes to kill remaining processes.

This started approximately July 4–6, 2026, shortly after the trackpad configuration was saved. Games worked normally before that.

Expected behavior

• Saving a trackpad mapping should not corrupt controller config files
• Games should launch normally with Steam Input enabled
• Stop should terminate game processes promptly

Actual behavior

• Game launch hangs (Steam UI shows launching; game window never appears)
• console-linux.txt shows repeated KeyValues parse failures:

  src/tier1/KeyValues.cpp (3120) : Assertion Failed: Error while parsing text KeyValues for resource In Game Actions
  src/tier1/KeyValues.cpp (3120) : Assertion Failed: Error while parsing text KeyValues for resource controller_mappings
  src/steamUI/controllerconfig.cpp (724) : No config for controller found locally, no config loaded as of now
  src/steamUI/controllerconfig.h (126) : Assertion Failed: CPrepareConfigWorker failed for AppID 2183900
  

• controller.txt shows registration error for the DualSense:

  BYieldingCompleteSteamControllerRegistration - Error committing registration completion of controller & account pair: FXA9954901415 Invalid Parameter
  

• Crash dump uploaded: CrashID=bp-b064b818-7a21-425a-ad11-a961f2260710 (2026-07-11 08:02:37)

Steps to reproduce

1. Connect a DualSense controller on Linux (Steam Input enabled)
2. Open Steam Input configuration for a Proton game (tested: Warhammer 40,000: Space Marine 2, AppID 2183900)
3. Configure trackpad bindings (touch/click actions) and save
4. Attempt to launch the game
5. Observe hang during launch (about 50% of the time); CPrepareConfigWorker failed in logs
6. All steam processes need to be killed before I can try again