breaking-serverless-1-shard-00-01(mongos-4.9.0-rc0)[mongos] CORE> db.check.insertOne({}) { "acknowledged" : true , "insertedId" : ObjectId( "6074aad76e02669be98128d8" ) } breaking-serverless-1-shard-00-01(mongos-4.9.0-rc0)[mongos] CORE> db.check.aggregate({$out: "10000" }) { "cursor" : { "firstBatch" : [ ], "id" : NumberLong( "0" ), "ns" : "CORE.check" }, "ok" : 1, "$clusterTime" : { "clusterTime" : Timestamp(1618258651, 15009), "signature" : { "hash" : BinData(0, "DmTvCASPK04UTi/hhR+6fpgIq/I=" ), "keyId" : NumberLong( "6948896105811673091" ) } }, "operationTime" : Timestamp(1618258651, 15009) } breaking-serverless-1-shard-00-01(mongos-4.9.0-rc0)[mongos] CORE> show collections 10000 → 0.000MB / 0.008MB check → 0.000MB / 0.008MB breaking-serverless-1-shard-00-01(mongos-4.9.0-rc0)[mongos] CORE> db[ "10000" ].find() TypeError: this ._collection.getName(...).indexOf is not a function