Why does updating quantity cause a cart error in Debut theme?

[lunacay]

Hello,

I get an error on my cart page when I update the quantity:

There was an error while updating your cart. Please try again.

This is the error in console.

[KKreations26]

I am having the same issue. I get a "There was an error while updating your cart. Please try again." error when I try to remove an item from my cart.