Buenas tardes:
Estamos teniendo el mismo problema. Adjunto el mensaje para que los desarrolladores puedan echarle un vistazo.
Error code: codingerror
* line 770 of /lib/dml/moodle_database.php: coding_exception thrown
* line 1290 of /lib/questionlib.php: call to moodle_database->get_in_or_equal()
* line 58 of /mod/quiz/addrandomform.php: call to question_get_top_categories_for_contexts()
* line 204 of /lib/formslib.php: call to quiz_add_random_form->definition()
* line 2507 of /mod/quiz/lib.php: call to moodleform->__construct()
* line 7719 of /lib/moodlelib.php: call to mod_quiz_output_fragment_add_random_question_form()
* line 415 of /lib/external/externallib.php: call to component_callback()
* line 228 of /lib/externallib.php: call to core_external::get_fragment()
* line 59 of /lib/ajax/service.php: call to external_api::call_external_function()