Can't change age in account settings

While I think never aging might be cool it doesn’t look like I can show that I had a birthday this summer and +1 how old (or young!) I am. When I increase age I and click “save” I get a “Whoops, looks like something went wrong.” error. Here’s the specific URL:
https://www.xertonline.com/account/settings/changeprofile

Cheers,

Sean