I logged into the iTunes store via Settings on a new iPhone 5s, and it automatically went to the "confirm your payment information" page.
I confirmed my method of payment (none), and it came back with an error, letting me know that:
Your account was changed while you were editing your account info. We were unable to save the changes. Please try again later.
I was currently logged into the Manage my Apple ID page when this error occurred (but was not actively editing anything), and once I logged out, I was able to confirm my payment method with no issue.
I was also able to log into the iTunes store on my Macbook and confirm the payment information with zero issue, but as far as I remember I was not logged in into the manage my Apple ID page.
Has anyone experienced this before? Does being logged into the manage my Apple ID page seem like a likely culprit for the error message I received?