Same here. I have a suspicion like they designed it for 5 queries/day and we just blew it.

So I tried it again after 24 hours on two different cards. First one worked right off the bat. Second one gave "System error" three times one row and worked on the fourth try. I think we’re looking at some real "enterprise-grade" software on MasterCard side.

If this is about the MC form, I found that if I pasted my CC number (such as from a pass manager), it would bork unless:

- I entered the number

- Then moved to the front of the input field

- Deleted a char, and re-entered it, because

- an end-of-field char change removes the whole number

Wait a sec, even two seconds, and the number will auto-obscure.

Then it works.

I got this in Chrome, it worked in Edge

Same here, “System error”