Error on server

Hi!

When i try to connect to my server this mesaagge appear

internalexception: io.netty.handler.codec.decoderexception:java.lang.indexoutofboundsexception: index: 27. size: 5

How could i fix this?
Any idea?

I´m using vanilla
And this mesagge appears on the console: [Server thread/INFO]: /190.162.242.64:62830 lost connection: Internal Exception: io.netty.handler.codec.DecoderException: The received string length is longer than maximum allowed (21 > 16)

Hi mi IGN was longer then 16 characters, so i changed it and actually works
So, thanks