After upgrading to version 8.1.2 my checkout does not work

[PushyMr]

Hello, after updating my prestashop from 1.7.8.2 to 8.1.2 with one click upgrade I encountered a lot of issues HOWEVER the biggest one is - my checkout is not working. After an order summary when i press button to proccess to checkout process i get this error

I cannot seem to find any relevant information in my logs and etc, furthermore, based on my controllers - I assume this would be the one used for checkouts
controllers/front/OrderController.php

it does not have an override and the only override controllers for front that i have are - 
override/controllers/front/CartController.php
override/controllers/front/ProductController.php

this a crucial issue for me, because we are about to upgrade our main server to be on prestashop 8.1.2 and we would loose a lot of business if I cannot fix this. I've been struggling for 2 weeks to solve this issue, with no success, anyone has any insight?
 

[musicmaster]

Are you sure you theme is 8.1 compatible?

[PushyMr]

I do not think this is theme related since I get the same error if I run the default theme, that was upgraded together with the whole shop

[JBW]

These is an override active (classes/Dispatcher.php) - check it's module origin, most probably it needs an update. You can deactivate the module/rename the override to checkj if it solves the problem

[PushyMr]

I did disable the module, but there was still the same error, the module that did an override is - Super speed by PrestaHero. 

[JBW]

Did you also rename the override? - not all overrides check if the module is deactivated

[PushyMr]

after renaming and turning off the module i get still the same error but now its

[PushyMr]

Okay i have some progress to report. After fully deleting my cache, my add to cart button on items is not working/responding, which is a big development. I had to clear my cache in the browser to find it. I assume the add to cart functionality is broken which leads to checkout not working, or it might still be there

[PushyMr]

Okay, small update, managed to fix the add to cart button and functionality, yet i still get the same error when i try to proceed into a checkout

[PushyMr]

okay small update, i did some logging inside dispathcer and i noticed this



I am baffled that when the classes in dispatcher are printed out on what controllers are found in controllers/front i can see the OrderController HOWEVER it doesn't get picked up when it tries to be called. These are my declarations for it

class OrderControllerCore extends FrontController

which should be fine, there are no overrides for it or anything, also when i checked in cache inside class_index.php i see that it was declared

'OrderControllerCore' => array ( 'path' => 'controllers/front/OrderController.php', 'type' => 'class', )

I'm completely lost on why it is not getting picked up, could it be that autoload was screwed up during the update? This is the only controller so far that doesn't work. Also since i updated from 1.7.8.2 to 8.1.2 i do get a lot of warning about deprecated code. Also my code is PHP 8.1