When i try to play on 1.7 on servers i crash

Put the summary of the bug you're having here
I crash when i try to play on 1.7 on a server
What I expected to happen was...:
Describe what you thought should happen here
i thought i would play on a server with 1.7
What actually happened was...:
Describe what happened here
it crashes
Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...Put game into 1.7 and press play
3. ...join a server then you crash