Why your tracking broke after moving to a new domain

Moving to a new domain feels like a simple swap, but to your analytics it is a new website. Cookies do not carry over, attribution resets, and if the old and new domains both exist for a while you can get messy self-referrals.

What a domain change does

• Cookies reset: first-party cookies are domain-specific, so every returning visitor looks brand new and attribution restarts.
• Config tied to the old domain: GA4 data stream URL, canonical tags and consent config may still reference the old domain.
• Self-referrals: traffic bouncing between old and new domains shows up as a self-referral.

How to migrate cleanly

1. Update the GA4 data stream to the new domain and keep the same property so history is preserved.
2. Set up 301 redirects from old URLs to new, so link equity and any in-flight sessions survive.
3. Add the old domain as a referral exclusion, or use cross-domain tracking during the transition.
4. Re-check consent config and canonical tags for the old domain.

Expect a visitor-count blip

Even done perfectly, you will see a short-term bump in "new" users because cookies reset, similar to the cookie-reset effect. That settles. What should not happen is tags going dark or conversions vanishing, which means the move left config pointing at the old domain.

Datahound are analytics and ad-tracking specialists. We fix broken GA4, Google Tag Manager and server-side tracking so every sale, form and call gets counted. Back to datahound.agency · All tracking guides · Self-referrals in GA4