Uncaught Notice: Undefined property: Product::$mpn after upgrading 1.7.1 -> 1.7.7

[Henrik41]

After upgrading from 1.7.1 -> 1.7.7.6 I am unable to add any products or modify a product and get this error:

 

Uncaught PHP Exception Symfony\Component\Debug\Exception\ContextErrorException: "Notice: Undefined property: Product::$mpn" at /home/xxxxx/public_html/src/PrestaShopBundle/Model/Product/AdminModelAdapter.php line 656

 

Symfony\Component\Debug\Exception\ContextErrorException: Notice: Undefined property: Product::$mpn at src/PrestaShopBundle/Model/Product/AdminModelAdapter.php:656 at PrestaShopBundle\Model\Product\AdminModelAdapter->mapStep6FormData(object(Product)) (src/PrestaShopBundle/Model/Product/AdminModelAdapter.php:459) at PrestaShopBundle\Model\Product\AdminModelAdapter->getFormData(object(Product)) (src/PrestaShopBundle/Controller/Admin/ProductController.php:667) at PrestaShopBundle\Controller\Admin\ProductController->createProductForm(object(Product), object(AdminModelAdapter)) (src/PrestaShopBundle/Controller/Admin/ProductController.php:457) at PrestaShopBundle\Controller\Admin\ProductController->formAction('115', object(Request)) (vendor/symfony/symfony/src/Symfony/Component/HttpKernel/HttpKernel.php:151) at Symfony\Component\HttpKernel\HttpKernel->handleRaw(object(Request), 1) (vendor/symfony/symfony/src/Symfony/Component/HttpKernel/HttpKernel.php:68) at Symfony\Component\HttpKernel\HttpKernel->handle(object(Request), 1, false) (vendor/symfony/symfony/src/Symfony/Component/HttpKernel/Kernel.php:200) at Symfony\Component\HttpKernel\Kernel->handle(object(Request), 1, false) (admin1/index.php:82)

- I checked my DB and mpn is where it is suppose to be.

- I checked the overrides and I am not overriding the AdminModelAdapter or product.php 

How do I even debug this??

Edited August 15, 2021 by Henrik41 (see edit history)