There was an error processing your order

Hello,

We are facing the problem after update.
We are getting multiple orders because customers keep clicking on Purchase button and facing this error.

We get order on the backend side, but no email is sent as confirmation.

Customer is facing this error message on our checkout page:

“There was an error processing your order. Please check for any changes in your payment method and review your order history before placing order again.”

I dont know what to do about it.

The strange thing is that I want to create a test order, I dont see this problem

What should I do to help you debug this?
This problem started to happen day or two before today.

The page I need help with: [log in to see the link]