Compatibility Report

• Name of the game with compatibility issues: Deadlock
• Steam AppID of the game: 1422450

System Information

• GPU: RX 6800XT
• Video driver version: 4.6 (Compatibility Profile) Mesa 26.0.5-arch1.1
• Kernel version: 6.19.12-artix1
• Link to full system information report as Gist: https://gist.github.com/iplly/6cfff066ca8c3d958a9fde190439fec6
• Proton version: Proton Experimental

I confirm:

• [x] that I haven't found an existing compatibility report for this game.
• [x] that I have checked whether there are updates for my system available.

steam-1422450.log

Symptoms

Deadlock crashes on startup with the error:
FATAL ERROR: Error reading from loaded packed store "S:\common\Deadlock\game\citadel\pak01_XXX.vpk".

The exact VPK file number (pak01_XXX.vpk) varies depending on the Proton version, as well as selected graphics backend (Vulkan/DirectX) and launch options.

The error appears in a dialog window after a few seconds of the loading screen, before the main menu is shown.

The issue occurs on modern Proton versions, including Proton Experimental and Proton GE.

Disabling other synchronization mechanisms (e.g., esync/fsync) does not resolve the problem.

The issue persists regardless of installation method:

• Steam installed from distribution repositories
• Steam installed via Flatpak

Cleaning cache files, reinstalling the game, and recreating the Wine prefix does not help.

The issue occurs on both X11 and Wayland sessions.

The game successfully launches only when using the launch option:
PROTON_NO_NTSYNC=1 %command%

Reproduction

Open Steam and click "Play" on Deadlock.

The game window appears, shows the loading screen for a few seconds, then a dialog with the VPK error appears and the game crashes.