There were problems processing your payment. Code (500)

Trying to give you money but I can't! Please advise

Are you using Paypal?

I am trying to take advantage of the half off for the makers packs, which takes into account that you have already purchased some points recently and halves the cost and subtracts the pre-purchased points you already had from the total you will get in the package. This deal is not accessible from inside of steam as far as I can tell, so I tried to use their website to conduct the transaction.

I do not use paypal, and will not ever again until either hell freezes over or those dbags stop interfering with wikileaks.

I have successfully made a purchase previously in game by enabling the steam overlay (it would not work otherwise), but the same payment source did not work from the website.

if you are still having trouble email them, it'll be quicker in the long run

Try using a different browser?

I am getting the same issue

All I know is that a 500 error typically is an internal server error, though not sure if that's also the case in this context.

Sorry I have no idea

I solved that problem with 5$.
First of all its the site problem,not your credit card.
Second you still can buy points 5$,10$,20$ but u can't buy the upgrade for your old pack.
I solved it with buying 5$ point AND SAVED THE CREDIT CARD INFO BY CLICKING THE SMALL BOX(the box that save your info) ABOVE THE PAYMENT BUTTON.
when u do that go back to the upgrade and buy it with the saved credit card and it will work.
i know its not the right way to do it but that will work

the $5 trick works :)

Yup had the same problem 5 $ tricks nice.