If you use Ajax to submit something to the server, and it comes back with a 500 status code, then that means that an error occurred on the server. So if that's what happened to you, then you have to look on the server to find out what the error was. Or if it's not your server, then you need to contact the people who manage the server and ask them to work with you to find the problem.
You showed up just in time for the waffles! And this tiny ad:
Building a Better World in your Backyard by Paul Wheaton and Shawn Klassen-Koop