Working my way through some other issues I am having with ajax checkout and 3D secure.

Here's my understanding of the checkout_payment page. On clicking the submit button, if ajax checkout payment is enabled, the center column is rewritten as a equivalent to the normal checkout confirmation page.

The problem is that the function submitonce() that is used in the form itself is not defined in checkout_payment . It is only defined in checkout_confirmation. So it creates an error.

Solution is just to include the submitonce function in checkout_payment as well.

I think that is correct but to be honest at this point I cannot get the ajax checkout to work at all. https://www.zen-cart.com/showthread....79#post1289779 . If anyone can help me with that then that would be great. Otherwise I will just work my way through it :-)