Why won't the "Confirm Order" button of woocommerce activate?

Question

WooCommerce

I add goods to the cart, go to the payment page, enter all the data, and the field with the product, price tag and payment methods is in a pending state, the payment button is also blocked. What could be the reason? It costs only cash on delivery.
I noticed this thing: if you delete the functions.php file, then everything works correctly. But in this file, it's just the creation of widgets, it's not clear what can interfere with work.

Answer 1

Perhaps it will come in handy for someone: in the functions.php file, you need to remove the closing ?php> tag at the end of the document.