From MoodleDocs

A required parameter (id) was missing.

This error happens when a webpage expects a parameter to be passed from another page (by post or cookie), and it fails to do so.

This happens sometimes when user session times out, due to inactivity, or when an URL that needs that mandatory parameter is instead directly typed in URL bar or invoked from browser bookmarks, like the SCORM Player page not being launched from a link in the course page.