can't join 1.7 servers

Put the summary of the bug you're having here

What I expected to happen was...:
Describe what you thought should happen here
I thought that i could just join a server to play on

What actually happened was...:
Describe what happened here
when I joined the game crashed but that happend with every server that was 1.7 but not on 1.8 or 1.6

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...
3. ...
1. I opened my launcher selected 1.7.9
2. minecraft opened
3. clicked on multiplayer
4. selected the server
5. tried to enter and then crashed