Urghhh!! I had this same problem about two weeks ago, but was able to update through the itunes store online. Now, however, no matter what I do (add other credit cards, change the information, delete it & re-enter it), I still keep getting an "invalid security code" message. Crap. At first I was worried it was my CC, but it's Apple, for sure. And good luck getting an answer today, when the new iphone drops. I can't update anything right now!! So frustrating. This is a ridiculous problem, especially since it was a prob on the last OS, as well as the new one, apparently.