After recently trying to enable Paypal’s ‘Hosted Payments Pro’ payment method in a Magento 1.6 install, I ran into an issue where the checkout wouldn’t procced past clicking the “Place Order” button. I tried this both on the Acumen template that was installed and all base/default themes and still had the same problem.
Investigating further it was clear the code was missing a template file that was present in earlier versions of Magento.
Copy the following file : /app/design/frontend/base/default/paypal/hss/iframe.phtml
Create the following folder structure and paste the iframe.phtml from above. : /app/design/frontend/base/default/paypal/hostedpro/iframe.phtml