The site seems to autocorrect it to MM/YYYY if you enter MM/YY. At least, when it works. Even when I entered the information in manually I got the same vague errors.
I wonder what the purpose of collecting at as MM/YYYY even is given that everyone will have an expiration date of 20YY for a long time; and that when they don't, the ones collected now will be expired so not an issue. Even if they store it locally as 20YY to avoid some bug in 2100 (which would be rather long term thinking at this point), it still makes no sense to collect it that way and to autocorrect. Why not just append the digits on the back end?
