I tried to go on the 1.7.9 version on MC PC to play on a server but it keeps crashing

Put the summary of the bug you're having here
BTW AFFECTS/VERSIONS ARE NOT 1.8.1

What I expected to happen was...:
I was expecting to play on a server that is on 1.7.9
BTW AFFECTS/VERSIONS ARE NOT 1.8.1
BTW AFFECTS/VERSIONS ARE NOT 1.8.1
BTW AFFECTS/VERSIONS ARE NOT 1.8.1
BTW AFFECTS/VERSIONS ARE NOT 1.8.1
BTW AFFECTS/VERSIONS ARE NOT 1.8.1

What actually happened was...:
I tried to log on the server but it crashed. (This happens to any server on 1.7.10 and 1.7.9 on my MC)

Steps to Reproduce:
1. Put in version 1.7.9 and save it
2. Join a server that is in 1.7.9
3. Then It will say that it has crashed