[Bug]: Add To Cart events not triggered [2025.7.1 and above]

[quentinlagache]

What is the location of your example repository?

https://github.com/Shopify/hydrogen/releases/tag/skeleton%402025.7.1

Which package or tool is having this issue?

Hydrogen

What version of that package or tool are you using?

2025.7.1 and above

What version of Remix are you using?

No response

Steps to Reproduce

Deploy skeleton on a live hydrogen store and check the related report: /analytics/reports/conversion_rate_breakdown

Works on 2025.7.0 and breaks starting from 2025.7.1

Expected Behavior

Add to cart event are triggered and shown in Shopify analytics.

Actual Behavior

[kdaviduik]

Hey @quentinlagache, thanks for reporting this! I am looking into it

[cheefkeefkev]

Hey @kdaviduik i have the same problem, do you have any information?
Thanks you :)

[quentinlagache]

Hey @kdaviduik — thanks for digging into this and proposing a fix in #3510.

I built and patched our production environment with the fix from #3510, but it didn’t resolve the issue — product_added_to_cart events are still missing on the backend side (Live view/analytics report).

Extra detail that might help: starting in 2025.7.1 (and later), the client still fires product_added_to_cart consistently, but the backend seems to ignore the POSTed event. Could this be related to the new cookie system introduced in 2025.7.1?

A new Storefront API proxy is now available in Hydrogen's createRequestHandler. This will be used to obtain http-only cookies from Storefront API.

From prior issues in this repo, it looks like product_added_to_cart depends on Shopify cookies being forwarded in request headers—so it’s possible something in that flow regressed.

I compared a known-working event payload from 2025.7.0 with the payload from 2026.1.0 and couldn’t spot any obvious structural issues.

Event for reference:

{
  "events": [
    {
      "schema_id": "custom_storefront_customer_tracking/1.2",
      "payload": {
        "source": "hydrogen",
        "asset_version_id": "2026.1.0",
        "hydrogenSubchannelId": "1000091091",
        "is_persistent_cookie": true,
        "deprecated_visit_token": "2e15c39c-be5d-4451-92e0-becede2ab5d0",
        "unique_token": "c689fe14-6f79-433c-8df0-8badf7c69857",
        "event_time": 1772122484243,
        "event_id": "9abb5699-2EC1-487A-173A-3219D94CEF9C",
        "event_source_url": "https://www.[domain].com/products/[product_handle]",
        "referrer": "",
        "user_agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.0.0 Safari/537.36",
        "navigation_type": "reload",
        "navigation_api": "PerformanceNavigationTiming",
        "shop_id": 92325970298,
        "currency": "USD",
        "ccpa_enforced": false,
        "gdpr_enforced": false,
        "gdpr_enforced_as_string": "false",
        "analytics_allowed": true,
        "marketing_allowed": true,
        "sale_of_data_allowed": true,
        "event_name": "product_added_to_cart",
        "cart_token": "hWN9Ed9hVlpz6MqnYHjAtevG?key=ee9db853bb4e417ea607a6f6919e13d5",
        "products": [...]
      },
      "metadata": {
        "event_created_at_ms": 1772122484243
      }
    }
  ],
  "metadata": {
    "event_sent_at_ms": 1772122484243
  }
}

[kdaviduik]

Hey @quentinlagache! Thanks so much for doing that, that's incredibly helpful!! I think it's related to the changes we made in Hydrogen for the new cookie system in 2025.7.1, but I'm not sure what the specific root cause is. I will dig into this more :)

[kdaviduik]

Update: I think I found the root cause, and it's something upstream of Hydrogen. Ie: the monorail events from Hydrogen are properly being sent, but the ingestion pipeline is erroneously filtering out the add to cart events from Hydrogen. This change was made to the ingestion pipeline around the same time we released Hydrogen version 2025.7.1.

If this indeed is the root cause, then I would expect to see the add to cart events also not populating the Shopify analytics in the admin even on Hydrogen version 2025.7.0 (which is the version before the new cookie changes). Note that I also back-fixed a bunch of historical Hydrogen versions, so a version like 2025.5.1 (despite being more "historical" than 2025.7.0) still has the new cookie changes, whereas 2025.5.0 doesn't.

I will test this out tomorrow, and if anyone can confirm if this is still an issue even on Hydrogen version 2025.7.0 (or other Hydrogen versions without the new cookie changes) that would be super helpful 😄

[frankl1nrg]

Hi @quentinlagache, do you recall when you first noticed this change? We’ve been using @shopify/hydrogen@2025.1.4 for a few months now, but we noticed a decline in the checkout completed rate around February 12th. I’m wondering if it is related to this issue.

We intend to upgrade to the latest version soon, but we will continue on @shopify/hydrogen@2025.1.4 for now until we learn more.