This is a common issue in GA4, but don’t worry—it can be fixed!
The “not set” message appears when GA4 doesn’t receive data in the order it expects.

Here’s what’s likely happening:

• Landing Pages Show “Not Set”: This can happen if the first action GA4 notices isn’t someone viewing a page. Imagine someone opens your site, gets distracted, and comes back later. If their first action is a click, but GA4 doesn’t catch the page load in time, it won’t know where they started.
• Source/Medium Shows “Not Set”: This happens when GA4 doesn’t see the “session_start” event. It’s like GA4 doesn’t know what brought the visitor to your site. The culprit is usually a misconfigured tag.

While it’s tough to eliminate this completely, here are some things that you can do to reduce it:

• Tag Ordering: Make sure the GA4 configuration tag fires first, before any other scripts. The page view event should come right after that.
• Consent Tools: If your site uses consent tools, set them up to send information to GA4 the right way. First, GA4 needs to know the default consent (before someone clicks the consent banner), then it needs the updated consent information once the visitor decides.
• User IDs: If you use User IDs, make sure every event uses the same User ID. If GA4 gets mixed signals, it may think the visitor is starting a new session.

By following these steps, you can help prevent that annoying “not set” from popping up in your data.

Hope this helps!