io.netty.handler.codec.DecoderException

I have been running bungee for months, no issues. Then today all players cause the following exception upon trying to connect.

http://pastebin.com/kLKx9W2g

Nothing has changed on the proxy or the servers.
I've tried updating to latest bungee and spigot, the same issue occurs.

Running on a dedicated server, following specs:
Operating system CentOS Linux 6.4
Kernel and CPU Linux 2.6.32-358.18.1.el6.x86_64 on x86_64
Processor information Intel(R) Xeon(R)...

io.netty.handler.codec.DecoderException