Why is my Shopify cart page not updating quantity when a user clicks the plus button?

Quantity update failures happen when AJAX cart scripts fail to send the quantity payload to Shopify’s cart api, or when your theme’s JS conflicts with automated discount calculations.

“Most minor website breaks are caused by simple script conflicts, legacy code blocks, or broken API handshakes. We identify and clear these issues immediately as a straightforward, one-time fix.”
— Jeff Bollettino, Managing Director, Ignite Conversions