Player gets kicked instantly after joining my server

Hello, a player who has been playing on my server for a while now has been strangely getting disconnected from my server every time he tries to log in. Here is the error message I am getting from the console:
12.05 22:01:40 [Server] INFO jsexpress left the game.
12.05 22:01:40 [Disconnect] User jsexpress has disconnected, reason: Internal Exception: net.minecraft.util.io.netty.handler.codec.DecoderException: java.lang.IndexOutOfBoundsException: readerIndex(11) + length(1) exceeds writerIndex(11): UnpooledHeapByteBuf(ridx: 11, widx: 11, cap: 11)
12.05 22:01:40 [Multicraft] jsexpress ran command Message of the Day
12.05 22:01:40 [Connect] User jsexpress, IP 24.116.185.52
12.05 22:01:40 [Server] INFO UUID of player jsexpress is 3cfe7351-d4df-4cb6-b63a-dedf95e3a51d

(Please note that my server panel reads the console from bottom up)

Please help me. Thanks

 

Ah, I used to get this error when I had a minecraft server. It'd happen every 30 minutes or so. I just decided to buy a server, and it fixed everything.