Supee-9767 saveBilling returning 500 after v2 Patch applied to 1.9.2.3 (formkeys present)

Question

After applying the Version 2 patch I'm having a problem with the patch where it seems that saveBilling() is returning 500 server error on checkout.

This is onepage checkout and I do use PayPal plus if that matters.

When I look at the form data the formkey value is there. So the missing formkey issue doesn't seem to be related to that.

I can disable formkey requirement in the admin side and the problem remains.

My template DOES NOT HAVE any /checkout/ stuff in it, so there are no files to add the often mentioned formkey's too --- that I can find.

Previously mentioned solutions I've tried:

1. https://gist.github.com/schmengler/c42acc607901a887ef86b4daa7a0445b

-- My template doesn't have a /checkout/ override so nothing to patch

2. Security Patch SUPEE-9767 - Possible issues?

Been through this thread a dozen times without success.

Any thoughts or suggestions would be greatly appreciated.

*** Update ****

I've chased the problem down to the following:

Call to undefined method Mage_Checkout_OnepageController::isFormkeyValidationOnChecko‌utEnabled();

* I found this function in Action.php *

Any thoughts on why they undefined method call occurring.

Answer 1

This issue may cause because of two things.

1. You are may be overwrite the \app\code\core\Mage\Checkout\controllers\OnepageController.php, this method is not there isFormkeyValidationOnChecko‌​utEnabled();

2. compiler may be enable. clear cache and recompile again .

Answer 2

Solution Follows

Thank you everyone for pointing me in the right direction. The problem ended up being that

app\code\core\Mage\Core\Controller\Front\Action.php

was being overwritten at

app\code\community\Mage\Core\Controller\Front\Action.php

This old code was taking precedent over the patched Action.php which includes the new function isFormkeyValidationOnChecko‌utEnabled(); and some other stuff.

In my case two solutions where available.

Solution 1: After inspecting the old Action.php it was found that this file was not required and simply deleting this file allowed the new version of Action.php to take over.

Solution 2: Was to copy the function isFormkeyValidationOnChecko‌utEnabled() and every other change made to Action.php over to the old Action.php to preserve any special behavior the template included in the first place.