This problem has two different solutions, both are easy:
1. If your server is not http://ripirc.org , consider removing it or commenting it out from the "friends" section of "settings"
(temporarily or permanently is your call)
2. If your server is http://ripirc.org , correct your "friends" section of "settings" so that old's URL is "http://null" or comment it out. Having a blank URL triggers minor frontend bugs for you, but more importantly, triggered federation problems for other users. A future software update should address this...