CS2 can’t join VAC-secure servers on Arch Linux (VAC signature invalid)

[Patrwyjana]

Steam and CS2 were working normally on my system before. After switching the kernel from linux (default) to linux-zen, I’m unable to join any VAC-secure servers.

I'm using Linux (Arch) and the issue happens consistently every time I try to join a VAC-secure server. CS2 works fine in offline mode.

Steps to reproduce:
– Launch CS2 from Steam
– Click on “Play” → select any game mode → press “Go” (Matchmaking).
– The client immediately shows “VAC signature invalid” without actually attempting to connect to a server.

Expected behavior:
The game should allow joining VAC-secure servers normally.

System info:
– Distribution: Arch Linux
– Steam version: 1759461205
– Kernel: 6.17.8-zen1-1-zen
– GPU driver: NVIDIA proprietary driver 580.105.08
– Proton version: Proton Experimental

Additional information:
– The game worked before with default kernel on my system.
– Reinstalling CS2 and verifying files did not fix it.
– Logging out of Steam and deleting shader cache did not fix it.
– I can provide more logs if needed.

[kisak-valve]

Hello @Patrwyjana, I initially transferred this issue report to the csgo-osx-linux issue tracker as a closer match than ValveSoftware, but reading further into the issue report, you're running the Windows variant of the game with Proton, which isn't supported in this issue tracker. Instead, issues with games run with Proton is being tracked on the Proton issue tracker, one issue report per unofficially supported game title. The compatibility report for running Counter-Strike 2 with Proton is at ValveSoftware/Proton#2704, which has similar feedback.

I'd reconfigure Steam to run the Linux native variant of the game.