Diagnostic tools
🔍 GTM Preview Mode
In the sGTM container click Preview — you see all incoming requests and how they're processed.
🌐 Browser DevTools
Network tab → filter your subdomain → verify the requests go out and return 200.
📊 GA4 Realtime
GA4 → Realtime → verify you see active users and events.
📱 Meta Test Events
Events Manager → Test Events → verify the server-side events and EMQ.
Common problems
❌ Data doesn't show in GA4
- Check that the transport_url in the web GTM points to the right subdomain
- Verify the sGTM container is running (Health check in the dashboard)
- Check the GA4 Measurement ID in the sGTM tag
❌ DNS wasn't verified
- DNS propagation can take up to 48 hours
- Verify the CNAME record with
dig sgtm.yourdomain.cz CNAME - On Cloudflare: turn off the proxy (orange → gray cloud)
❌ SSL error
- The SSL certificate is generated automatically after successful DNS verification
- Wait 5-10 minutes after DNS verification
- If the problem persists, contact support
❌ A high number of errors in the sGTM Preview
- Verify the tags have the correct API keys/tokens
- Check the triggers — a wrong trigger = the tag won't fire
- Check the data format in the dataLayer on the site
Need help?
If you can't resolve the problem, contact our support at [email protected]. For PRO-plan customers we provide priority support with an SLA of up to 2 hours.