What should the Developer verify to identify the issue of users not able to submit coupon codes?

To determine the cause of users being unable to submit coupon codes, it's essential to understand the role of the cart service in the Salesforce B2C Commerce ecosystem. The cart service is responsible for managing the shopping cart, including the application of discounts and coupon codes.

If the cart service is not configured correctly, it may not process these coupon codes correctly, abandoning the user's request or returning errors that prevent successful submission. Ensuring that the cart service has the necessary configurations, such as links to the relevant promotions and discount handling logic, is crucial for regular functionality.

Verifying the cart service allows the Developer to confirm that everything regarding coupon application operates as expected, ensuring a smooth user experience when applying discounts. Other options, while they may be relevant in broader contexts of site security or session management, do not directly address the functionality specific to coupon submissions and would not be the first points of investigation in this scenario.