Exception - Serialization of 'Closure' is not allowed

[haietza]

Several of our courses that have questionnaires in use have questions with position numbers less than 1. When the course is restored to our current Moodle instance (3.6.5+ Build: 20190718) and a user tries to edit and save a question, the Exception - Serialization of 'Closure' is not allowed error is displayed. It looks like this is being generated by line 745 of locallib.php in questionnaire_check_page_breaks. The questions can be edited without error on previous versions of Moodle. Changing the position numbers of all questions to be greater than 0 resolves the issue in 3.6.5. However, it would be helpful if the position numbers were updated on Moodle upgrade, or if the positions less than 0 did not throw an exception. Thank you!

[mchurchward]

What version of questionnaire are you seeing this with?

[haietza]

@mchurchward Version 3.6.1 (Build - 2019052400) 2018110101 of the questionnaire module.