I need to change the value of the shipping cost when the user select the shipping address on my magento 2 checkout. Using some params of the products they are buying and the params of the shipping address.

So I decide to create a Plugin to execute some code before and after shipping is selected. Reading on magento 2 documentation (Plugins (Interceptors) | Magento 2 Developer Documentation) I created an aroundMethod(). Well I created and I added only the sample code I got from the documentation and a simple var_dump() but when I execute the code on my checkout I get this javascript error:

Cannot read property 'items' of undefined at ko.subscription.callback (totals.js:18)

This seems like my plugin doesn't return something of necessary.

This is my Plugin:

The declaration on <vendor>\<module>\etc\di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/con
     <type name="Magento\Checkout\Model\ShippingInformationManagement">
         <plugin name="get_shipping_info" type="<vendor>\<module>\Plugin\ShippingCalculate" sortOrder="1" disabled="false"/>

Then my plugin code <vendor>\<module>\Plugin\ShippingCalculate


namespace <vendor>\<module>\Plugin;

class ShippingCalculate

     * @var \Magento\Checkout\Model\Session
    protected $_checkoutSession;

     * @var \Magento\Framework\App\Request\Http
    protected $_request;

     * @var \Magento\Quote\Api\CartRepositoryInterface
    protected $_quoteRepository;

     * @var \Magento\Catalog\Model\ProductFactory
    protected $_productFactory;

     * ShippingCalculate constructor.
     * @param \Magento\Checkout\Model\Session $checkoutSession
     * @param \Magento\Framework\App\Request\Http $request
     * @param \Magento\Quote\Api\CartRepositoryInterface $quoteRepository
     * @param \Magento\Catalog\Model\ProductFactory $productFactory
    public function __construct(
        \Magento\Checkout\Model\Session $checkoutSession,
        \Magento\Framework\App\Request\Http $request,
        \Magento\Quote\Api\CartRepositoryInterface $quoteRepository,
        \Magento\Catalog\Model\ProductFactory $productFactory
        $this->_checkoutSession = $checkoutSession;
        $this->_request = $request;
        $this->_quoteRepository = $quoteRepository;
        $this->_productFactory = $productFactory;

     * @param \Magento\Checkout\Model\ShippingInformationManagement $shipping
     * @param callable $proceed
    public function aroundSaveAddressInformation(
        \Magento\Checkout\Model\ShippingInformationManagement $shipping,
        callable $proceed,
        \Magento\Checkout\Api\Data\ShippingInformationInterface $addressInformation
        $quote = $this->_quoteRepository->getActive($cartId);
        echo $cartId;

        $returnValue = $proceed($cartId, $addressInformation);
        if ($returnValue) {
            // No Code here
        return $returnValue;

1 Answer 1


You are doing var_dump and echo in the code. This ends up being send in the response and it is not parsed properly on the frontend because the response is not a valid json. Remove them and all should work.

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