CartThrob checkout form returning wrong subdomain

Question

I just upgraded a site from CartThrob 2.1.3 to 2.5 (along with updating EE to 2.7.3). Everything seems to be fine, but I'm having a glitch during the checkout process. It may very well not have anything directly to do with CT, but I'm stumped as to what's going on. Any suggestions would be really appreciated. Here's the situation:

I have set up a subdomain for the upgraded site, for example, beta.testsite.com (the regular site url is formatted like www.testsite.com). During the checkout process, I have an initial https page where the customer enters their name, as well as choosing a shipping option and entering a shipping address. When submitted, that page is supposed to return the second checkout page, where credit card information gets input.

What's happening, though, is that instead of returning https://beta.testsite.com/cart/checkout2, it's returning https://www.testsite.com/cart/checkout2 instead. (www instead of beta)

I've checked the template for the first checkout page, the cart scripts file that gets embedded, and the htaccess file -- none are explicitly calling the www version of the domain.

Any suggestions on what might be the culprit?

(I realize this is a somewhat vague issue with lots of potential variables, but I'm stumped. Thanks in advance.)

Answer 1

1. Make sure you have EE's admin > general settings > URL to the root directory of your site is set correctly.

2. Make sure the return parameter on the checkout_form is something like this:

   return="template_group/template"

And doesn't include a hard coded URL.

There are some other things that could be wrong if this is an MSM site. But the two above are the most common problems.