Easy Anti-Cheat #

Sometimes, seemingly randomly, you can get an EAC error during the VRChat startup/login screen. It looks like a message box, with the title “Anti-cheat Error”, no actual message text, and a single button labeled “Quit”.

Recommended Workaround #

Wrapper script for starting VRChat: startvrc.sh on GitHub

Set startup options for VRChat: /path/to/startvrc.sh %command%

If you’re using extra env vars, they should go first: PRESSURE_VESSEL_FILESYSTEMS_RW=/run/user/1000/monado_comp_ipc /path/to/startvrc.sh %command%

Root Cause #

We are still trying to determine the cause.

It is likely caused by a race condition. Closing unnecessary apps or otherwise lowering your CPU usage before starting VRChat seems to make the EAC error happen significantly less often. It is safe to crank the CPU usage back up after the home world has loaded.

The following sections do not fix the issue, but are still kept on the wiki to dispel rumors and record research.

(Outdated) glibc dt_gnu_hash #

Previously, we believed it to be related to an incompatible glibc version. However, upon further testing, this turned out to be insufficient.

In other games with EAC, getting past the EAC splash screen had required glibc to be built with a specific flag to work.^1,2 (--hash-style=both)

Flatpak Steam includes this flag, however Flatpak Steam is not recommended for VR.

As of 2024-02-09, Arch Linux no longer ships with this flag.

• Arch users could use this EAC-specific glibc from the AUR: https://aur.archlinux.org/packages/glibc-eac
• Gentoo users could enable the fix using the hash-sysv-compat USE flag on sys-libs/glibc.

To reiterate, this glibc flag does not appear to fix VRChat’s particular flavor of EAC failures.