My customers have started to report an error when they have made their selection and are wishing to advance through the payment process. They supplied additional information if this helps:
The online checkout is not working properly. “ERROR HTTP 500”. It happened twice that’s why we got orders #2781 & # 2782.
After it happens for the 1st payment, I logged back in and the shopping carts still have 3x waiting for payment.
Therefore, did the second time and got the same error.
Reading a little into it, it maybe a problem associated with my PayPal module, but I have no way to know.