Where those (not set) landing pages in GA4 come from

Google brought the landing page report back to GA4, and the moment you open it one thing stands out: a sizeable pile of (not set).

At its core the value means the session's first event wasn't a pageview. Or that there's a session with events only and no pageviews at all.

You can check this in Explorations: build a session-scoped segment where landing page = (not set), open the Users Explorer and work through those sessions.

Say you're reading an article. You look something up, make coffee, get distracted. After 30 minutes of inactivity your session expires. The same happens when the clock passes midnight.

Scroll or click after that and a new session starts. That scroll or click is now the first event. No pageview, so (not set).

The second cause is ordering. If an event fires before gtm.js, GA4 misses the pageview as the session's starting point.

A badly implemented cookie banner is by far the biggest offender here. It often fires an event before the container has loaded.

Legacy code on the page can clash with your GTM implementation too. And if you have an app, the same property may hold both app and web data. Add hostname as a secondary dimension to rule that out.

• Extend the session timeout if that suits your site. You can go up to 7 hours and 55 minutes.
• If you run GA4 through GTM, make sure nothing fires before the gtm.js event. Start with your consent banner.
• Build your own landing page report using the landing page + query string dimension. It usually tells you more than the standard one.
• For full analytical freedom, rebuild it in BigQuery.