We've moved websites. Our Magento site now works fine, but when you go to checkout through Authorize.net it simply goes back to the shopping cart.
If you try to process your order through PayPay, it goes to the PayPal site and everything works until it goes back to the site. When you click 'Submit Order' - we are getting a 500 error.
We are on Community Edition 1.9
Any help would be greatly appreciated !!