The GA4 tracking errors I find most often

None of these are exotic. They're the kind of thing that slips in during a launch or a site update and then sits there for months, quietly making your reports wrong. Go through the list with your analytics open.

1. Revenue doesn't match your backend

Compare last month's revenue in GA4 with your shop system. Some gap is normal because of consent and blocked scripts, but a big or growing gap means something is broken. Find that out before you trust any conversion rate.

2. Purchases are counted twice

If the purchase event fires every time someone reloads the thank you page, or comes back to it from an email, you count the same order more than once. Send the transaction ID with every purchase and check for duplicates.

3. Payment providers steal the credit

When customers return from a payment page, that visit can show up as a referral from the payment provider. Suddenly your best "channel" is a bank. Add those domains to the list of unwanted referrals.

4. Currency or value is missing

Ecommerce events without a currency, or with the value sent as text, can show zero revenue or odd totals. Check a few real events in DebugView.

5. Consent mode isn't working as you think

Either tags fire before people accept, which is a legal problem, or they never fire at all after acceptance, which is a data problem. Test both paths yourself: accept, decline, and check what reaches GA4.

6. Your own team is in the data

Developers, marketers and customer service browsing the site all day add up. Define internal traffic and filter it out, at least from your main reports.

7. Cross domain tracking is missing

If checkout, booking or payment happens on another domain, sessions break in two and conversions get the wrong source. Set up cross domain measurement for every domain in the journey.

8. Ecommerce events are incomplete

view_item, add_to_cart and begin_checkout without the items array, or with different product IDs than the purchase, make funnel and product reports useless. Compare the parameters across events for the same product.

9. Data retention is still on the default

GA4 keeps detailed event data for only two months unless you change it. That limits explorations later. Set it to the longest period your plan allows.

10. Event names are a mess

Three versions of the same event, "(not set)" everywhere and custom events nobody remembers creating. Agree on a naming convention, document it, and clean up what's there.

Before you test anything

An A/B test is only as good as the data behind it. If two or three of these sound familiar, fix them first. It's exactly what my GA4 and tracking audit covers, and it's step one in a good CRO audit.