Hi,

At the end of an hotpot activities, there is an error message which happen when activity completion tracking is active in the course.
"Unexpected manual completion state for 34674: -1
Error code: err_system"

In the file mod/hotpot/submit.php ligne 98:
$completion->update_state($cm);
should be replace by:
$completion->update_state($cm, COMPLETION_COMPLETE);

Here, "possibleresult" paramater is "COMPLETION_UNKNOWN" => that's why error appears:

switch($possibleresult) {
case COMPLETION_COMPLETE:
case COMPLETION_INCOMPLETE:
$newstate = $possibleresult;
break;
default:
$this->internal_systemerror("Unexpected manual completion state for {$cm->id}: $possibleresult");

If you could have a look and confirm.
Best regards.