Further to this, it has been identified that the mongo cursor is inside a function which takes in values for field_name to be projected.
Cursor = db.coll_name.find({}, {field_name:1})
But there are instance where no projection is required and therefore field_name becomes empty string.
This has not caused problem when the version was 4.2.23
But now version is 5.0.4
Wanted to know is this occuring as a part of this upgrade.