Hi, the problem is solved. Thanks John. (see here: https://github.com/estebanlm/voyage/issues/6) 2 Points: 1) RKAPerson selectMany: {('_id' -> ('75b900000000000000000000')). } asDictionary. is wrong. I have to call e.g. RKAPerson selectMany: {('_id' -> (OID value: 16r55CDD2B6E9A87A520F000001)). } asDictionary. 2) For correct generating of OID, I use this commit http://smalltalkhub.com/#!/~MongoTalkTeam/mongotalk/versions/Mongo-BSON-Henr... Esteban, what do you think about putting this version of Henrik commit into the ConfigurationOfMongoTalk? Regards Sabine -- View this message in context: http://forum.world.st/Mongo-find-object-by-id-tp4842231p4843195.html Sent from the Pharo Smalltalk Developers mailing list archive at Nabble.com.