According to: https://docs.mongodb.com/manual/reference/method/db.collection.update/#mongodb30-upsert-id

This query:

db.collection.update( { "_id.name": "Robert Frost", "_id.uid": 0 },
   { "categories": ["poet", "playwright"] },
   { upsert: true } )

Should throw an error in mongodb > 3.0, but at least in mongo 3.2.6 I get no errors when executing this query.