Database
[{"_id":{"$oid":"632a11c91f786f7d86d7633a"},"List":[{"Name":"WithError","Error":"duplicate"},{"Name":"WithOutError"}]}]
Query
db.collection.update({},[{"$set":{"List":{$map:{input:"$List",as:"element",in:{$cond:{if:{$ifNull:["$$element.Error",false]},then:{Name:"$$element.Name",Error:["$$element.Error"]},else:"$$element"}}}}}}])