Server Error via Web console

So I checking my web console via ftp. And this is all I see

**
(Filename: Line: -1)

MissingMethodException: Method not found: ‘BanList.Add’.**

Is this right? My server has been crashing ever few hours. Is this error ok? Is it causing that?

FTP= FPSplayers.
Running Rust++
Population 80-120

Just making sure this isnt causing the error to crash the server.

Thanks.

Bump any help