I found this page and was able to resolve my problem by changing the ordering to web20cart per the suggestion. But I was not using the ajax cart, I was using the Modern themed cart at the time.
The issue came in after the domain name selection process when the cart is supposed to move to the hosting package choice I’d get a 404 error. I noticed the web address had changed from the ?ccce=cart to /cart.php which of course didn’t work because the WordPress bridge is not in the same folder as the whmcs install. So the problem with other cart themes may be that somewhere in the checkout process the link to the whmcs bridge is getting replaced with the actual whmcs location.
/cart.php?a=add&pid=1
vs
/?ccce=cart&a=add&pid=1
Hope this helps get the issue actually resolved and not just a work around.
– Keith
