I am using GA4 Event Builder to understand how I can do a vanilla HTTP POST request to record a GA4 event. I used the builder to input what I believe to be the correct “Measurement ID” and “API Secret“. All the other details such as Client ID and User ID are just arbitrary inputs. When I press the “Validate Event” button on the Event Builder, it pauses for a moment and keeps returning the “This event has not been validated” message.

Even if I try a similar request via HTTP POST (to the https://www.google-analytics.com/debug/mp/collect endpoint), I get a 204 return code (or 200 if in debug mode) but nothing else to tell me that something might be going wrong. I have never seen any event appear in the real-time analytics.

Does anyone know what I could be doing wrong?