Why your Shopify cart count stopped updating

A store’s header cart count had stopped keeping up. You’d add something, and the little number by the cart icon wouldn’t move until you reloaded the page. Everything else worked, the item really was in the cart, the count was just stale.

What we did

The cause was a theme setting. The store had switched its cart from a slide-out drawer to a full cart page, and the header counter had been wired to update off the drawer opening. With the drawer gone, the event it was listening for never fired, so the number only refreshed on a full page load. Nothing was broken in the usual sense, the counter was simply waiting for something that no longer happened. We reconnected the count to update when the cart itself changes rather than when a drawer opens, and it kept up again.

What to take from it

Changing one setting in a theme can quietly unhook something two steps away that depended on the old behaviour. A cart counter that only updates on reload is the kind of thing you stop noticing on your own store, because you know the item’s really in there, while a first-time customer reads it as the add-to-cart not working. If you switch your cart between a drawer and a page, or change anything else that central, it’s worth clicking through an add-to-cart afterwards as if you’d never seen the site before.