Troubleshooting Problems Adding Products to Cart
Symptom
Clicking Order Now on the shopping cart product selection page (cart.php) or following a direct product order link (for example, http://example.com/whmcs/cart.php?a=add&pid=1) appears to refresh the page and shows the product selection page again.
When this happens, the ordering process may not proceed to the product configuration or view cart stage.
Cause
This issue is due to outdated templates. The application of a WHMCS update failed to apply the corresponding changes to custom themes or order form templates.
Solution
Apply the latest theme and order form template updates to your custom themes and templates. You can find the required template changes in the Templates section of each version's Release Notes.
If you are updating across multiple versions (for example, from WHMCS 8.2 to 8.4), you must apply all of the template changes sequentially. For example, when moving from WHMCS 8.2 to 8.4, you must apply the WHMCS 8.3 template changes first and then apply the WHMCS 8.4 template changes.
If you purchased WHMCS from a third-party vendor, contact them to obtain the necessary update for compatibility with the new version of WHMCS.
Workaround
You can work around this problem by switching to the stock system theme (Twenty One) and order form template (Standard Cart) that the latest changes automatically udpdate.
- Go to Configuration > System Settings > General Settings and choose the General tab.
- Change System Theme to Twenty-One.
- Go to Configuration > System Settings > General Settings and choose the Ordering tab.
- Change Default Order Form Template to Standard Cart.
- Click Save Changes.
If any product groups specify custom order form templates, you must also update those settings.