Checkout errors cost more than any other bug on your store

Why checkout errors are different

Every part of your store matters, but no part matters as much as the checkout. A visitor who reaches the checkout has already made the decision to buy. The consideration phase is over. Conversion intent is at maximum. An error at this stage doesn't just fail to convert a visitor — it actively destroys a sale that was already won.

The business case for checkout monitoring is straightforward: if your checkout has a 5% error rate and 100 people reach checkout per day, that's 5 lost sales per day that were already in the bag. At an AOV of £80, that's £400/day, £12,000/month, £146,000/year in preventable revenue loss. These aren't abandoned carts in the traditional sense — they're completed decisions that your site failed to fulfil.

The unique challenge of Shopify checkout monitoring

Shopify's checkout presents a specific technical challenge for monitoring: your theme scripts can't run in checkout. Shopify's checkout pages run in a sandboxed environment controlled entirely by Shopify. Third-party theme scripts, app embeds, and custom JavaScript are not executed there. This is by design — it protects payment security — but it means that any monitoring tool that relies on your theme to inject its tracking code is completely blind once a customer reaches the checkout URL.

The only sanctioned way to instrument Shopify checkout is through two APIs: the Web Pixel API for storefront and checkout events, and the Customer Events API for post-purchase flows. Bloodhound uses both.

What Bloodhound captures in checkout

Through the Web Pixel, Bloodhound captures the following checkout funnel events:

• page_viewed — visitor reaches the checkout URL
• checkout_started — checkout session initiated
• checkout_address_info_submitted — shipping information entered
• checkout_shipping_info_submitted — shipping method selected
• checkout_contact_info_submitted — contact details confirmed
• payment_info_submitted — payment details submitted
• order_created — order successfully placed
• thank_you_page_viewed — post-purchase confirmation viewed

For each event, Bloodhound records the timestamp, session ID, page URL, and any error state. Drop-offs between stages are visible in the funnel analysis: if 100 sessions reach “checkout started” but only 60 reach “payment submitted”, that 40-session drop is quantified and can be investigated.

Common checkout errors and what causes them

Payment widget failures

Stripe, PayPal, Klarna, Afterpay, and other payment processors all inject JavaScript into the checkout. Their SDKs can fail for various reasons: rate limiting, network errors, outdated browser APIs, or version incompatibilities with Shopify's checkout updates. These failures typically prevent the payment form from loading or the payment submission from succeeding.

Address validation errors

Some themes and apps add custom address validation that can fail for edge cases: postcodes in non-standard formats, international address fields, or businesses with long address lines. These produce JavaScript errors that may silently prevent the “Continue” button from functioning.

Discount code failures

The checkout API endpoint for discount code validation can return errors that are handled poorly in some implementations. A network timeout during discount validation might leave the checkout in a broken state without surfacing a user-visible error message.

Shopify Plus checkout customisations

Merchants on Shopify Plus can add custom JavaScript to checkout via checkout.liquid. This customisation code has more scope to introduce bugs — particularly with each Shopify checkout update that may change the DOM structure the customisation was written against.

Post-checkout failures

The order confirmation page and post-purchase upsell flows run separate JavaScript from the checkout. Errors here don't lose the sale but can affect customer experience, loyalty app integrations, and conversion tracking.

Funnel drop-off vs error: knowing the difference

Not every checkout drop-off is a technical error. Users genuinely abandon carts for non-technical reasons: unexpected shipping costs, indecision, price comparison, being interrupted. Good checkout monitoring distinguishes between:

• Error-correlated drop-offs: sessions that dropped off at a stage where a JavaScript error was captured in the same session
• Clean drop-offs: sessions that dropped off without any error, likely for behavioural reasons

The error-correlated drop-offs are the ones you can fix. The clean drop-offs need CRO work, not engineering work. Bloodhound separates these, so you can prioritise appropriately.

The checkout monitoring benchmark

A healthy Shopify checkout has:

• Error rate below 1% of checkout sessions
• Zero payment widget failures (any is too many)
• Checkout initiation to order complete conversion above 60%
• No error regressions after theme or app updates

If your checkout error rate is above 2%, you almost certainly have a specific, fixable bug. With Bloodhound monitoring active, you'll know about it within minutes of it appearing.