"Unknown error occured! Contact staff"
No /f, /msg, /r etc
You cannot, as that would pose a risk to CubedCraft itself.
If I could logon as Partydragen, I could obtain permissions to give my main account op/perms/rank and destroy the server.
Now technically you can do what zephix did
I'm not gonna show how to do that here, and they probably have already patched the bug.
I caught someone by the nick of GoF**kYourself saying "its so shitty"https://imgur.com/a/wmMwkqB