Adhoc task failed: core\task\asynchronous_copy_task,Attempt to assign property "subquestions" on false

The Health check does not show what course.  So ...

make a query of the mdl_question table for
id, parent, name, createdby where name like '%somethinginnameofquz% to get info on what user.

createdby is the user id - example shows 2075

Query of mdl_users:
select username from mdl_user where id = 2075;

Then investigate that users profile to see what courses and thus quizzes via GUI.

'SoS', Ken