In the 18.3.0 release on October 9, 2023, we’ve made a significant update to how Piwik PRO recognizes sessions. Now, whenever a user ID changes during a visitor’s session, Piwik PRO automatically starts a new session.
Previously, if the user ID changed within the same session, Piwik PRO treated it as a single session. This led to inaccurate data because user ID information was replaced by new IDs within the same session. This typically occurred when multiple individuals shared the same device or when someone logged in and out of various accounts.
Here’s an illustration of session detection before and after the change.
The updated session recognition method will give you a more precise count of users and sessions. This change is similar to what currently happens when campaign parameters or referrers change within a session.
Just keep in mind that you may see an increase in the number of sessions after this change.