I am trying to set up a configurable product but all I get when I click on the product is a completely blank page. No header, etc, nothing. View Source shows no code is output at all. What could be causing this? Here is the url to the configurable product: https://www.design-a-cake.co.uk/photocake-edible-cake-topper-pumpkin-lanterns.html Thank you.
Your page has no error: see screenshot below
So in short, your issue seems to be that the rendering does seem to be stopped somehow. To debug, you may go in the product controller and put some logs to check what's happening. If you have installed some plugins, you may look at a possible controller taking over product in your Magento system.