Cause
This error is raised by the deletion of members of a child class, if the number of members of a collection processed during a delete of the children does not agree with the initial number of children.
If the destructor of a child changes the keys of a collection so that children are missed (because children later in the collection are changed to have a key less than or equal to the child being deleted), those children can be left as orphans (with pointers to the deleted parent).
Action
Change your application code to ensure that the destructors do not change the order of members of the collection while they are being deleted.