Does not send goods to the Opencart cart. Why?

Question

opencart

Raised the version of ocstore 2.1 -> 2.3. Everything seems to be set, but adding a product does not work. It seems that something is sent, but the goods do not fall into the basket. Where should you look? Doesn't show any errors.

Answer 1

The problem was in the catalog/controller/checkout/cart.php file. I suspect it's because of the custom code. The difficulty is that this file practically does not throw errors and almost had to wang to determine the problem.