This fails db.responses.update({ "$or":[ {"itemId":24, "importDocumentId" : "90016201230095201111"} , {"itemId":24, "importDocumentId" : "90016201230085201111"} ]}, {$set:{responseStateCode:2}}); can't do non-multi update with query that doesn't have a valid shard key This works db.responses.update({ "itemId":{$in: [24,25] }, "importDocumentId":{$in: ["90016201230095201111", "90016201230085201111"] }}, {$set:{responseStateCode:2}}); ------------- FindAndModify -------------- This fails db.responses.findAndModify({ query:{"$or":[ {"itemId":24, "importDocumentId" : "90016201230095201111"} , {"itemId":24, "importDocumentId" : "90016201230085201111"} ]}, update : {$set: {responseStateCode:2} }}); Thu Dec 13 16:12:32 uncaught exception: findAndModifyFailed failed: "db assertion failure" This works db.responses.findAndModify({ query:{ "itemId":{$in: [24,25] }, "importDocumentId":{$in: ["90016201230095201111", "90016201230085201111"] }}, update : {$set: {responseStateCode:2} }});