Why is my add to cart button failing when a product is already in the cart?

[daphimo]

Hi guys,

I am facing an error with my add to cart.

So instead of default product form I am using the custom form to submit the item to the cart. So when I send item to cart for the first time it works but when there is already a product present in the cart this time my add to cart button is not working. What is wrong i couldn't understand.

[Sweet_Savior_3]

hello @daphimo 

please send me your Store Url