Unexplained traffic

Product Support
1

Your software
My Mautic version is: mautic:6.0.9-20261021-fpm
My PHP version is: PHP 8.3.36 (cli) (built: Oct 21 2026 16:00:25) (NTS)
My Database type and version is: mariadb:12.3

Your problem
My problem is:

Following the recent PHP vulnerabilities, I’ve just created a fresh install using the official Docker image that includes patched PHP. I restored a MySQL backup from the previous instance to MariaDB. I’ve configured the new instance to point to the MariaDB database and I’m using a different domain name and implementing on a new server. I’ve kept the old instance alive and accessible on the old domain. I’ve updated the GTM variable for the Mautic URL and published the new version. Once I published the new version, I could see contacts being created in the new instance. However, I’ll still seeing contacts created on the old instance. I’m at a loss to figure out what’s going on. Presumably GTM implements cache busting to prevent old versions from being used.

Any ideas on how I can troubleshoot this?

These errors are showing in the log:

NA

Steps I have tried to fix the problem:

Confirmed each step.

2

Hi Genesys

I would first verify which Mautic endpoint is actually receiving the tracking requests. This is usually not a cache-busting problem inside Mautic.

Open the website in a private browser window and check DevTools → Network. Filter for mtc.js, mtc, or mtracking.gif, then inspect the Request URL. Every tracking request should point only to the new Mautic hostname.

Also check:

  1. GTM Preview mode: confirm the active published container version and search all tags, variables and custom HTML for the old Mautic URL.
  2. The rendered page source: make sure there is no second GTM container or hard-coded tracking script containing the old URL.
  3. CDN, reverse-proxy and page caches: purge the cached HTML and verify the response directly from the origin server.
  4. Browser service workers and local storage, if your site uses them.
  5. Access logs on both Mautic servers at the same timestamp. This will show whether the old instance is receiving real tracking requests or whether the contacts are only visible because both installations share data.
  6. The database configuration of both containers. Confirm that the old and new installations use different database hosts, database names, credentials, prefixes and persistent volumes. Running both instances against the same database can produce confusing results during a migration.

Changing a GTM variable does not remove an old tracking script that is still present in cached HTML, another tag, a second container or a custom integration. Mautic’s tracking code contains the Mautic hostname directly, so the Request URL is the most reliable way to identify the source of the contact creation.

The official tracking documentation describes the same endpoint-based behaviour: