Click continue in the billing step returns to the cart.
updated my 1.9.2.3 to 1.9.3.7. Version is correct, magereport shows all patches correct. No applicable errors is sysem.log.
I have set enable form key validation and disabled as well. cleared caches , turned them off. Forced an update again but still no go. Teh error occurs with key validation on or off and on EVERY template including default and rwd.
There are similar symptoms written up in the forum but nothing applicable. Am at a loss at this point
More info error.log shows
PHP Fatal error: Call to undefined method Mage_Checkout_OnepageController::isFormkeyValidationOnCheckoutEnabled() .../app/code/core/Mage/Checkout/controllers/OnepageController.php on line 369.
Method isFormkeyValidationOnCheckoutEnabled IS defined in action.php.