Can't Get On Friend's Server

I am trying to get on my friends server - coopercraftv2.mcph.co and i can't.

Every time i try to go on it my minecraft crashes.

Please try to help.
Thanks

P.S. i am using minecraft 1.7.9 because the server was made on that version not 1.8.1.
I couldn't get 1.7.9 as the version it affects.