Buy button not working in opencart 2.1.2?

Question

opencart

Good afternoon!
Such a problem with opencart (version 2.1.2), when you click on the buy button on a product, the following errors pop up:

To be honest, I have already run out of ideas about what it could be, I reviewed the common.js file 3 times, everything is correctly spelled out there

Answer 1

You send an ajax request to add to the cart somewhere in the wrong place.
Look in the devtools in the Network tab where the request goes, what data is transferred there and what the response comes from.