We had the same error.
Could add $$ to the cart, but "An Error Has Occurred" when confirming the purchase. Checked my CC info, correct number. But, we had incorrect expiration date as the card had been recently updated.
Download in progress...
how did u forward your date
fixed it. turns out it was because i forwarded the date by a few years to avoid cinavia. how ridiculous is that? anyways problem solved.