never-terminatedThe course never closed its session, so the LMS may discard the final state of the attempt.
Progress saves while the learner works, then the last stretch is missing. Someone finishes the final page and comes back to find themselves a few slides short, or completed-but-unscored.
A SCO opened a session but no Terminate (2004) or LMSFinish (1.2) call was recorded before the session ended.
Terminate is the point at which the LMS is told the attempt is over and may safely persist it. Systems differ in how forgiving they are: some commit whatever they hold, some roll back to the last explicit Commit, and some leave the attempt open and confuse the next one.
Call Terminate on the course's own exit path rather than relying on the window closing. Browsers do not guarantee that unload handlers finish, and on mobile they frequently do not run at all. If exit is driven by a Close button, that button should terminate before it navigates.
A session cut short by a closed tab can legitimately show this. It matters when it happens on the normal exit path.
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Stuck on this one, or seeing it only in a particular LMS? That is usually a short conversation — scormspecialist.co.uk.