Checkout errors for some customers

First of all upgrade your Gold Cart version ( https://getshopped.org/extend/premium-upgrades-files/ )

Now you are saying that you are using Shipping on your store but i looked at your website and on the checkout page you have no shipping calculator enabled.
Maybe you hid it using CSS ?

Also please verify that the WPeC theme files in your theme folder and the default ones that come with the Plugin don`t have big differences in the code.
Some times outdated WPeC theme files in the active theme causes lots of problems.

I have now upgraded my Gold Cart version.

I’m not sure what you mean when you say I have no shipping calculator enabled. Here are screenshots to illustrate the process I see when I go through checkout.

When I first get to the checkout page, this is what I see:

https://drive.google.com/file/d/0BzVHDGJeVssRcUw3SEVqZnJ2S1U/edit?usp=sharing

After selecting a shipping destination (in this case, Canada), the red text pops up reminding me to click “Calculate” to recalculate the shipping rate, as illustrated here:

https://drive.google.com/file/d/0BzVHDGJeVssRVHBrMENBTTlMaEk/edit?usp=sharing

After clicking “Calculate” the rest of the form appears, as illustrated here:

https://drive.google.com/file/d/0BzVHDGJeVssRQUxBN3UtTG1lcWs/edit?usp=sharing

After filling in all the required fields as illustrated above, and seeing that the subtotal, tax and shipping rate have all been calculated, I click “Purchase” and I am then taken to PayPal payment.

I have tried this same process using all of the areas the store ships to (different rates for Canada or USA/UK), and every time after selecting the initial shipping destination and clicking Calculate, shipping successfully recalculates.

If the shipping calculator was not enabled, as you suggest, then how could I go through this process to payment successfully myself? The store has processed multiple orders since the error was first reported, so why is checkout working successfully for some customers and not for others? I will take a closer look at the theme files as you suggest, however again, if this was the problem, why would it be broken for some customers but not for me or for other customers who are successfully sending payment?

I just loaded the store and the shipping calculator does not show up for me on the first page load.
It might be something with your theme.
Please post a Premium support topic with Getshopped
https://getshopped.org/resources/premium-support/

I’m confused as to why you are not seeing the shipping calculator, as in every test I’ve run on every browser including mobile devices, I have not had any problems with it whatsoever.

I replaced the wpsc-shopping_cart_page.php file in my theme with the one from the current version of the plugin’s default theme folder, and so aside from some minor visual customizations I made to match the rest of the website, this should not be an issue.

I will do as you suggest and start a support topic with Premium support.

I wanted to post a follow-up to this thread as an FYI to the developers — I was finally able to replicate the error and it turns out that the error would only occur when free shipping was activated. The store in question is set to give free shipping for orders over $150. So if the order total was less than $150 or the item was exempt from shipping, the checkout form would process correctly and continue to PayPal. If the order was more than $150, it breaks the shipping calculator. It’s like the form thinks shipping has not been selected and gives the error. I have rolled back to WP e-Commerce 3.8.13.4 and now everything works correctly.