Compatibility Report

• Name of the game with compatibility issues: Forza Horizon 6
• Steam AppID of the game: 2483190

System Information

• GPU: AMD Radeon RX 7900 XT 20GB
• Video driver version: Mesa 26.1.1-arch1.2
• Kernel version: 6.12.91-1-MANJARO
• Link to full system information report as Gist:
• Proton version: Proton Experimental (bleeding-edge), Proton Hotfix, GE-Proton 10-34

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.

Symptoms

After the Hotfix 2 update (version 364.933, May 27 2026), the game no longer launches. Steam reports the game as running but no window ever appears. The process stays alive indefinitely. Before this update the game ran fine for a week.

The Proton log immediately spams EXCEPTION_ILLEGAL_INSTRUCTION (0xc000001d) across multiple threads from the moment the process starts, and never progresses past this point. Ends with a SIGSYS (blocked syscall).

Reproduction

1. Install Forza Horizon 6 on Manjaro Linux with AMD GPU
2. Set Proton to any recent version (Hotfix, Experimental bleeding-edge, GE-Proton 10-34)
3. Launch the game
4. Steam shows game as running, no window appears, ILLEGAL_INSTRUCTION loop starts immediately and never stops

steam-2483190.log