If you are tracking user interactions, either on-page or server-side, you are likely to have at least some sessions that are not associated with a landing page. This can happen when a session includes no pageviews or when the first hit in a session is not a pageview.
There are three potential causes to sessions with no landing page in Google Analytics (Universal Analytics; GA4 is different). All are connected with event tracking.
To troubleshoot this problem, always start by creating a segment for sessions where the landing page is “not set.” Once you have done that you can begin to identify the likely culprit.
Here are the three main potential causes:
Events delivered server-side (via GA’s Measurement Protocol) often create a distinct session. Because this session does not take place in a browser or follow a pageview, the session does not get attributed to a landing page.
How to troubleshoot: Apply your “not set landings” segment to an event report such as “top events.”
You might now be able to easily recognize which events are server-side. If they are, that is the likely cause and you can consider this to be expected behavior. Your “not set” landing pages are not a sign of a tracking problem.
Conversely, if the associated events are events that take place on pages — you can add “page” as a secondary dimension to determine this — this is not likely to be the problem. That’s because events that cause not-set landing pages are not associated with pages at all.
When you are tracking on-page events such as video plays and downloads you will sometimes see sessions with not-set landing pages due to “session refresh.”
For instance, when a user has left a page open in the browser for longer than the session timeout period (usually 30 minutes) and that user returns and starts interacting again, a new session will begin in Google Analytics — starting with the first hit delivered beyond the timeout.
When that first hit is an event rather than a pageview the session will report a landing page “not set.”
How to troubleshoot: Apply your “not set landings” segment to the audience overview report.
If session refresh is causing this issue, that segment will include a disproportionately high percentage of “returning users.” That is your first hint that session refresh is the cause.
You can dig a little deeper using the user explorer report. Observe the actions taken by users who have sessions with no landing page.
If they have a normal-looking session (such as one that starts with a pageview) and then the first hit in their next session is an event, and it is more than 30 minutes later than the prior hit, this is likely to be a session refresh.
A simple implementation mistake also can result in not-set landing pages.
On-page events should not fire before pageviews. However, there are many cases where certain events fire upon page load.
For example, a third-party service might populate additional audience info in an event; a split-testing service might fire an event to indicate that a test experience has been entered; or a scroll tracking event might indicate 25% scroll on page load.
If any of these types of events happen to fire before the pageview tag on the page, that can cause the session to begin without a landing page value.
How to troubleshoot: Follow the steps above, regarding session refresh.
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