Server error "Weapon stats writing failed: -404"

I administer a dedicated server, and I can't figure out what this error is, anyone have an idea?  

By default weaponstats are reported via sv_weaponstats_file.

You can just nullify that cvar... `sv_weaponstats_file ""`.

I have the same problem too.  My friend created a server on Windows with some basic configuration and stats seem to work fine.
I created a server on mac and I never see my stats online and I get these errors in the console at the end of each game:
Player stats writing failed: -401
Weapon stats writing failed: -404

I don't know how to fix this. Please help!