Exception thrown on Quiz re-calculate statistics

[Syxton]

'Learning Check #19' (138454) in course 2122W ES201-04 (88534) has most recent attempt finished at 23/02/22, 17:41:00 so re-calculating statistics for 18 attempts, start time 24/08/23, 13:51:43 ...
Exception - Call to a member function getMessage() on string

Error code: generalexceptionmessage

• line 35 of /filter/wiris/integration/lib/com/wiris/plugin/impl/FolderTreeStorageAndCache.class.php: Error thrown
• line 119 of /filter/wiris/integration/lib/com/wiris/plugin/impl/TextServiceImpl.class.php: call to com_wiris_plugin_impl_FolderTreeStorageAndCache->storeData()
• line 70 of /filter/wiris/integration/lib/com/wiris/plugin/impl/TextServiceImpl.class.php: call to com_wiris_plugin_impl_TextServiceImpl->jsonResponse()
• line 71 of /filter/wiris/integration/lib/com/wiris/plugin/impl/TextFilter.class.php: call to com_wiris_plugin_impl_TextServiceImpl->mathml2accessible()
• line 188 of /filter/wiris/integration/lib/com/wiris/plugin/impl/TextFilter.class.php: call to com_wiris_plugin_impl_TextFilter->math2Img()
• line 227 of /filter/wiris/integration/lib/com/wiris/plugin/impl/TextFilter.class.php: call to com_wiris_plugin_impl_TextFilter->filterMath()
• line 21 of /filter/wiris/integration/lib/com/wiris/plugin/impl/TextServiceImpl.class.php: call to com_wiris_plugin_impl_TextFilter->filter()
• line 84 of /filter/wiris/subfilters/php.php: call to com_wiris_plugin_impl_TextServiceImpl->filter()
• line 62 of /filter/wiris/filter.php: call to filter_wiris_php->filter()
• line 513 of /lib/filterlib.php: call to filter_wiris->filter()
• line 188 of /lib/filterlib.php: call to moodle_text_filter->filter_stage_post_clean()
• line 230 of /lib/filterlib.php: call to filter_manager->apply_filter_chain()
• line 1360 of /lib/weblib.php: call to filter_manager->filter_text()
• line 1058 of /question/engine/lib.php: call to format_text()
• line 268 of /question/type/multichoice/questiontype.php: call to question_utils::to_plain_text()
• line 87 of /question/classes/statistics/responses/analyser.php: call to qtype_multichoice->get_possible_responses()
• line 746 of /mod/quiz/report/statistics/report.php: call to core_question\statistics\responses\analyser->__construct()
• line 716 of /mod/quiz/report/statistics/report.php: call to quiz_statistics_report->analyse_responses_for_questions()
• line 669 of /mod/quiz/report/statistics/report.php: call to quiz_statistics_report->analyse_responses_for_all_questions_and_subquestions()
• line 945 of /mod/quiz/report/statistics/report.php: call to quiz_statistics_report->get_all_stats_and_analysis()
• line 108 of /mod/quiz/report/statistics/classes/task/recalculate.php: call to quiz_statistics_report->calculate_questions_stats_for_question_bank()
• line 405 of /lib/classes/cron.php: call to quiz_statistics\task\recalculate->execute()
• line 208 of /lib/classes/cron.php: call to core\cron::run_inner_scheduled_task()
• line 125 of /lib/classes/cron.php: call to core\cron::run_scheduled_tasks()
• line 186 of /admin/cli/cron.php: call to core\cron::run_main_process()