The online businesses thrive to provide the best user experience to the customers. A seamless and smooth checkout experience in necessary for eCommerce stores to close more deals. Sometimes, the eCommerce businesses face technical bottlenecks that directly affect their revenue. One such issue is the Undefined Method in getConfigurableAttributeCollection in Magento 2.3.3. After upgrading to Magento 2.3.3, many of the store owners complained that the customers are facing issues during the payment process. After the checkout, a long error is displayed to the customers on the Magento 2 page, rather than redirecting to the payment page. I have figured out a simple solution to solve this issue in Magento 2. You need to add a simple condition in the MagentoConfigurableProductHelperProductOptionsLoader::load(ProductInterface $product).