I created a preference override for Magento\Quote\Model\Quote\Item\CartItemPersister in my own module. But I get this error in the browser developer console:

Total: Type Error occurred when creating object: Magento\Quote\Model\Quote\ShippingAssignment\ShippingAssignmentProcessor, Argument 3 passed to Magento\Quote\Model\Quote\ShippingAssignment\ShippingAssignmentProcessor::__construct() must be an instance of Magento\Quote\Model\Quote\Item\CartItemPersister

instance of Company\Configurator\Rewrite\Magento\Quote\Model\Quote\Item\CartItemPersister given


<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">

    <preference for="Magento\Quote\Model\Quote\Item\CartItemPersister"

It seems like I also have to override Magento\Quote\Model\Quote\ShippingAssignment\ShippingAssignmentProcessor and swap to my rewrite class there, but this does not seem to be the official way?

UPDATE: I've completly overriden Magento\Quote\Model\Quote\ShippingAssignment\ShippingAssignmentProcessor but now I get

Total: Type Error occurred when creating object: Magento\Quote\Model\QuoteRepository\LoadHandler\Interceptor, Argument 1 passed to Magento\Quote\Model\QuoteRepository\LoadHandler\Interceptor::__construct() must be an instance of Magento\Quote\Model\Quote\ShippingAssignment\ShippingAssignmentProcessor, instance of Company\Configurator\Rewrite\Magento\Quote\Model\Quote\ShippingAssignment\ShippingAssignmentProcessor given, called in /var/www/company/m2/vendor/magento/framework/ObjectManager/Factory/AbstractFactory.php on line 121

Whats the best way to solve this?

2 Answers 2


I was able to solve it with a plugin instead of an override


In this case, your only option would be to create a subclass of Magento\Quote\Model\Quote\Item\CartItemPersister and implement your changes there. This can get messy when the parent class implements a lot of private methods which usually means that you need to copy the parent class to the subclass and then add your customizations on top.

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