Unique Error?

I've never seen anyone post this error before, Nor would i like to see this anywhere.

I'm blurring out the IP of the user who joined for this unique error, but let me describe the error, then i'll give you the console of my Server's hub.

So yesterday, I went to change my connection throttle times to -1, because whenever you would go from one server, then back to the other; within a few minutes; You'd recieve connection throttled. So i went in all my bukkit.yml instances and changed the...

Unique Error?