Your conversion tracking died the day you redesigned the site

We moved our booking off a third-party scheduler onto our own subdomain. Good change. It also broke the conversion that told Google Ads a booking had happened, and nothing anywhere said so.

There is no alert for this. The account keeps running. The reports keep drawing. The number is simply zero, and zero is indistinguishable from a bad month until somebody thinks to check the plumbing.

Why it breaks, in order of frequency

• The thank-you URL changed. Most conversions are defined as a visit to /thank-you. The redesign renamed it, or the new form shows an inline message and never navigates anywhere at all.
• Booking moved to a subdomain and the tag was never installed on the new host, so the page that proves the conversion is the one page with no tracking on it.
• Cross-domain linking is missing. The visitor crosses from your site to the booking host and is counted as a brand new person who arrived from nowhere. The conversion may fire and it attributes to nothing.
• A consent banner was added and now blocks the tag until an interaction that most visitors never make.

The three-minute test

1. Open your site in a private window. Go through the whole thing as a customer: click the ad if you can, fill the form, submit it, land on whatever page it lands on.
2. Watch Google Analytics realtime while doing it. Your own visit should appear, and the conversion event with it.
3. Use Google Tag Assistant on the site, including on the booking subdomain, to confirm the tag is present and firing where you think it is.
4. In Google Ads, open Goals and check the last conversion date for each conversion action. That single column tells you which ones are dead.

Then delete your test conversion, or at minimum write down when you did it, so next month's report is not explained by you.

The expensive part

Broken tracking is not only a reporting problem. Smart Bidding learns from conversions. Feed it zero and it does not idle politely — it keeps buying clicks and has no way to prefer the good ones, so the budget drifts toward whatever is cheapest rather than whatever works.

Every day in that state is money spent teaching the system nothing. It costs the same as a good day.

Make it a habit rather than a rescue

• Test the form yourself on the first of the month. It takes three minutes and it is the highest-value three minutes in the ad account.
• Re-test after any site change at all, including the ones that seem cosmetic. Especially the ones that seem cosmetic.
• Have the form send you a plain email as well. If the emails stop and the conversions do not, you know where to look, and vice versa.
• If your booking lives on another host, set cross-domain linking up once and check it exists whenever the tool changes.

The reason this one belongs on a list about search is that all of it is downstream of the same mistake: assuming that because nothing reported an error, nothing broke.