Crashing on Muitiplayer Server

Put the summary of the bug you're having here Minecraft Muitiplayer Crashing

What I expected to happen was...:
Describe what you thought should happen here going in the server

What actually happened was...:
Describe what happened here was Minecraft Crashing

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...
3. ..