Crash when joining home server

Joining my home server causes the client to crash. Everything used to work but this issue seems to have arrived in the last day or so.

Steps to Reproduce:
1. Started Minecraft
2. Joined my home minecraft server
3. Client crashes

Joining another home server (newer) doesn't seem to cause the crash, so I'm guessing it's due to my server being older and having been upgraded from 1.7 (I think) up to now.