Non existent visitor ids

I am experiencing an issue with an application that uses Matomo to track visits to a website, and also submit usage events to a different idsite in an app. It’s mildly complex, so I’ll describe a workflow to demonstrate my issue.

  • User visits site, they are given a visitorId
  • User clicks button in site to open a new widget on a window with a different domain. We pass the vistorId to the widget when the button is clicked.
  • Upon widget completion, we request the data for the visitorId via the API, and perform actions on it.

What I have discovered is that, in the widget, the visitorId we pass from the main site to the widget, does not actually exist as a visitorId in the Matomo DB. This an intermittent issue.

Are there circumstances in which Matamo will create a visitorId and not save it?

Caveat: I am also using the same Piwik instance to track widget usage. This submits the usage events to a different idsite (same idsite for all widget instances). What I don’t know is if this potentially a factor, since I cannot reliably reproduce.


So far no solution to this issue is making itself apparent. Does anyone have any thoughts or directions I can look at this.