Consider the following document: { "_id" : 1, "name" : "Aphex Twin" , "albums" : [ { "_id" : 1, "name" : "Selected Ambient Works 85–92" , "tracks" : [ { "_id" : 1, "name" : "Xtal" }, { "_id" : 2, "name" : "Tha" }, { "_id" : 3, "name" : "Pulsewidth" } ] } ] } I want to update the track with the name "Tha" to "**Tha" for demonstration purposes. Using update with $set, I tell Mongo to find the document with _id of 1, an album sub document _id of 1, an album tracks sub-document with _id of 2 and update it's name. I will show the behaviour from the console: 3.0.0-rc6 (Incorrectly updates the first track name and not the matching second): Unable to find source-code formatter for language: console. Available languages are: actionscript, ada, applescript, bash, c, c#, c++, cpp, css, erlang, go, groovy, haskell, html, java, javascript, js, json, lua, none, nyan, objc, perl, php, python, r, rainbow, ruby, scala, sh, sql, swift, visualbasic, xml, yaml MongoDB shell version: 3.0.0-rc6 connecting to: issue-test > db.bands.findOne(); { "_id" : 1, "name" : "Aphex Twin" , "albums" : [ { "_id" : 1, "name" : "Selected Ambient Works 8592" , "tracks" : [ { "_id" : 1, "name" : "Xtal" }, { "_id" : 2, "name" : "Tha" }, { "_id" : 3, "name" : "Pulsewidth" } ] } ] } > db.bands.update({ "_id" : 1, "albums._id" : 1, "albums.0.tracks._id" : 2 }, { "$set" : { "albums.0.tracks.$.name" : "**Tha" }}); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.bands.findOne(); { "_id" : 1, "name" : "Aphex Twin" , "albums" : [ { "_id" : 1, "name" : "Selected Ambient Works 8592" , "tracks" : [ { "_id" : 1, "name" : "**Tha" }, { "_id" : 2, "name" : "Tha" }, { "_id" : 3, "name" : "Pulsewidth" } ] } ] } 2.6.7 (Incorrectly updates the first track name and not the matching second): Unable to find source-code formatter for language: console. Available languages are: actionscript, ada, applescript, bash, c, c#, c++, cpp, css, erlang, go, groovy, haskell, html, java, javascript, js, json, lua, none, nyan, objc, perl, php, python, r, rainbow, ruby, scala, sh, sql, swift, visualbasic, xml, yaml MongoDB shell version: 2.6.7 connecting to: issue-test > db.bands.findOne(); { "_id" : 1, "name" : "Aphex Twin" , "albums" : [ { "_id" : 1, "name" : "Selected Ambient Works 8592" , "tracks" : [ { "_id" : 1, "name" : "Xtal" }, { "_id" : 2, "name" : "Tha" }, { "_id" : 3, "name" : "Pulsewidth" } ] } ] } > db.bands.update({ "_id" : 1, "albums._id" : 1, "albums.0.tracks._id" : 2 }, { "$set" : { "albums.0.tracks.$.name" : "**Tha" }}); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.bands.findOne(); { "_id" : 1, "name" : "Aphex Twin" , "albums" : [ { "_id" : 1, "name" : "Selected Ambient Works 8592" , "tracks" : [ { "_id" : 1, "name" : "**Tha" }, { "_id" : 2, "name" : "Tha" }, { "_id" : 3, "name" : "Pulsewidth" } ] } ] } 2.4.12 (Correctly updates the matching sub-document): Unable to find source-code formatter for language: console. Available languages are: actionscript, ada, applescript, bash, c, c#, c++, cpp, css, erlang, go, groovy, haskell, html, java, javascript, js, json, lua, none, nyan, objc, perl, php, python, r, rainbow, ruby, scala, sh, sql, swift, visualbasic, xml, yaml MongoDB shell version: 2.4.12 connecting to: issue-test > db.bands.findOne(); { "_id" : 1, "name" : "Aphex Twin" , "albums" : [ { "_id" : 1, "name" : "Selected Ambient Works 8592" , "tracks" : [ { "_id" : 1, "name" : "Xtal" }, { "_id" : 2, "name" : "Tha" }, { "_id" : 3, "name" : "Pulsewidth" } ] } ] } > db.bands.update({ "_id" : 1, "albums._id" : 1, "albums.0.tracks._id" : 2 }, { "$set" : { "albums.0.tracks.$.name" : "**Tha" }}); > db.bands.findOne(); { "_id" : 1, "albums" : [ { "_id" : 1, "name" : "Selected Ambient Works 8592" , "tracks" : [ { "_id" : 1, "name" : "Xtal" }, { "_id" : 2, "name" : "**Tha" }, { "_id" : 3, "name" : "Pulsewidth" } ] } ], "name" : "Aphex Twin" }