We have been receiving more and more complaints of merchants seeing their cart crash due to 429 errors, not only on the /cart/add.js and other mutation endpoints, but on the /cart.js endpoint as well. The issue is particularly visible when connecting through a VPN (I have used NordVPN P2P connectio…

429 errors affecting real shoppers have been resolved. The remaining issue is CLI-specific, and we’re still working on a proper fix. Thanks to @bakin11 for sharing a great workaround, which I’d recommend following to get unblocked in the meantime. To keep CLI discussion in one place, I’m going to c…

I understand, but this was never an issue before and lots of cart experience are built on complicated use of the Cart API. The use of the Cart API is not limited to simple cart additions or quantity changes, due to multiple apps having to cooperate without clean standards and due to having to work …

Agree with @Zak that this was not an issue before Jan 24th. Testing and site monitoring has become a problem as BrowserStack and other site monitoring tools (Sematext) are unable to proceed with any cart requests anymore. I’m seeing 429 responses even on the initial cart request when using these to…

We recently introduced stricter bot protection, but it should not impact legitimate traffic for valid requests. A couple of optimizations to consider: Prevent having multiple apps make the exact same request within the same minute. Ensure requests are unique. For example, avoid updating the same …

Hi @Paige-Shopify , thanks for responding. I am mostly encountering the issue when testing our themes on both a development store and on a merchant store. We perform updates for existing clients that are running a custom theme and perform changes in our local dev environment. When running Shopify CL…

We are getting 429 errors too, when simply doing a single await fetch(“/cart.js”).then(e => e.status) request.

We use an app to Add To Cart. We had a sale going the 11th-16th and our customers were complaining that they would click on Add to Cart and it just spins and spins, never adding the product to cart. They couldn’t add various products to their cart. We verified that on certain random products, thi…

I can add to this, we have a client which recently also started to see this exact issue. It has been reported by multiple of their customers, so it’s not only when testing this happens. The client uses the premium theme Enterprise, and the theme standard code makes a GET request to “/cart.js” before…

In my case I could only reproduce it in local environments, but around a week ago a merchant reported the issue too in their live store, all cart requests suddenly started responding 429 (without generating more than a couple requests a minute), and they weren’t using a VPN.

Thank you to everyone jumping in to share your experience with this. If possible can you provide this information so we can investigate this further: A request ID for an affected cart (can be to any /cart endpoint as 429 requests don’t typically get one) Whether and how you encounter a challenge …

Aggressive bot detection with 429 errors AJAX Cart API

Online Store and Theme Development

Zak February 17, 2026, 1:19pm 28

but it should not impact legitimate traffic for valid requests

Exactly, but it does

Ajax API aggresive 429 status responses when running theme locally

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Aggressive bot detection with 429 errors AJAX Cart API

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