The server-side container is deployed and running, but you see no incoming data in its preview. Almost always the problem is the link between web GTM (in the browser) and the server-side container — configured via a transport URL.
Symptoms
- No requests arrive in the server-side container's preview.
- Client-side measurement (web GTM) works, though.
- Conversions don't arrive anywhere, even though the tags in the server container are configured.
Why it happens
For web GTM to send data to the server-side container, the GA4 configuration must have the server container's address set (transport URL / server container URL). If it's missing or wrong, the browser sends data straight to Google instead of to your container.
What to check
- 1. Transport URL. Verify the GA4 configuration in web GTM points to the correct address of your server container (your first-party domain/subdomain).
- 2. Domain and SSL. The container address must be reachable over HTTPS with a valid certificate.
- 3. Preview both containers. Run preview for the web and server containers at the same time and watch whether the request from the site reaches the server.
- 4. Consent. If measurement is tied to consent, test with consent — otherwise nothing is sent.
How to verify the fix
After fixing it, you should see incoming events in the server container's preview and their effect in GA4 DebugView.
The basics of how the server-side container works are in the server-side GTM basics docs. The overall verification routine is covered in how to verify server-side tracking works.