What version of ViaVersion are you using? Type /ver viaversion

What version of Spigot are you using? Type /ver

What plugins are you using? Type /plugins

Are you using any additional software like BungeeCord? If so, what software and version? (Please list your plugins as well)

How does this error happen? login? Using an item?

Is there an error in the console? Use pastebin.com. Is there a kick message?