The reservation made with the id of `586e70e956943734038b4568` does not have a date attached to it. Please run this script from the mongo console to assign it to `01/01/2020`, and then follow up immediately. db.reservations.update({"_id" : ObjectId("586e70e956943734038b4568")}, {$set: { "event": ObjectId("52a0b5f25dc14953e14ce65d") }})