Hi
we get this error in only one attempt:
Fatal error: Call to a member function summarise() on null in /var/www/html/moodle-3.3.2/question/type/ddimageortext/questionbase.php on line 65
This error blocks the cron-script and attempts arn't closed.
This Quiz have 1534 Attempts
64 $selected = $this->get_selected_choice($place->group,
$response[$this->field($placeno)]);
-> 65 $summarisechoice = $selected->summarise();
Did you, by any chance, edit that question after some students had attempted it? (You can verify that by comparing the time of the quiz attempts with the time the question was last edited.)
The code should be robust in that case, but until that is fixed, the work-around is: don't do that!
I ask the course trainer, most probably yes, he edit question after quiz was started.
cron continued his work after excluding the line: //$summarisechoice = $selected->summarise()