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", a message referring to a filepath that failed to validate integrity, and a single button labeled "Quit".
- The filepath in the message always refers to a file within `steamapps/common/VRChat`.
- The EAC error can trigger even when all these files are completely pristine.
- The problem file can be different each time.
- EAC doesn't care about any of the files in `AppData/LocalLow/VRChat`. This means yt-dlp.exe, logs, the local cache, etc are not subject to integrity checks.
- Getting multiple EAC errors in a row is very possible. But if it triggers 10 out of 10 attempts in quick succession, call us.
- Some EAC info is also written to the VRChat log file.
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The message box used to have no actual message text. The message returned in a VRChat update, possibly on the serverside and without a steam depot update, sometime between 2024-03-25 and 2024-03-28.
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.
In other games with EAC, getting past the EAC splash screen had required glibc to be built with a specific flag to work.<sup>[1],[2]</sup> (`--hash-style=both`)
