I have the same problem and am seriously struggling now after days of trying to fix this bug!
Most customers that visit the shop cannot continue. They all get stuck on the checkout page.
I can replicate this but buying a product and the clicking on the continue buttons, then going back up the checkout page and click modify and then click the continue buttons again. It stops working.
The buttons just do not work. Unless you wait a while and come back to it then they work again.
I have the shoppica theme, but I have now disabled it and running the default shopping cart.
Things I have done :
• re-uploaded all the checkout files in catalog/controller/checkout and catalog/model/checkout
• Checked the following at its ok: /catalog/controller/checkout/register.php on line 28 i change the utf8_strlene to utf8_strlen.
• Disabled shipping extensions
• Uninstalled and re installed payment options
• Replicated on default OC
Does anyone know a solution? PLEASE!
Im going to re apply my shoppica template so my customers have some where to go even tho most cant buy anything!
I have OC 18.104.22.168