My Minecraft server won't work anymore? (Mac)?

So a couple of days ago I made a server for the snapshot 13w35b, so I could play with my friends, because I made a mini game. It worked great, but today, when I updated the server to 15w35e (I just copied the world, downloaded the new server and replaced the world with the other one), my friends couldn't join, but I could. The IP didn't change or anything the server just kept pinging and would eventually say that they couldn't connect. The application I use for my friends to play on it (I think, I only watched a Youtube tutorial) is Port Map. I use the smaller, lighter IP at the top that says "Port Map on…", but my friends use the big bold IP. And that worked for them before. None of the IP's I gave them worked. I don't know what the problem is.