Consider that we have a document with some fields. If I try to delete like below, it can happen sometimes that it is not deleted in some occasions without returning any exception and/or WriteResult error:

DBObject q = new BasicDBObjectBuilder().start().add("_id", new ObjectId(id)).get();
DBCursor res = mongoDBConnector.getContacts().find(q);
if (res.hasNext())

{ mongoDBConnector.getContacts().remove(res.next()); }

However, I can delete successfully by using the field _id of the document like below:

DBObject q = new BasicDBObjectBuilder().start().add("_id", new ObjectId(id)).get();
mongoDBConnector.getContacts().remove(q);