diff --git package-lock.json package-lock.json
index c09426b894..444d08baf5 100644
--- package-lock.json
+++ package-lock.json
@@ -4314,9 +4314,9 @@
 			"integrity": "sha512-q/UEjfGJ2Cm3oKV71DJz9d25TPnq5rhBVL2Q4fA5wcC3jcrdn7+SssEybFIxwAvvP+YCsCYNKughoF33GxgycQ=="
 		},
 		"backbone": {
-			"version": "1.3.3",
-			"resolved": "https://registry.npmjs.org/backbone/-/backbone-1.3.3.tgz",
-			"integrity": "sha1-TMgOp8sWMaxHSInOQPL4vGg7KZk=",
+			"version": "1.4.0",
+			"resolved": "https://registry.npmjs.org/backbone/-/backbone-1.4.0.tgz",
+			"integrity": "sha512-RLmDrRXkVdouTg38jcgHhyQ/2zjg7a8E6sz2zxfz21Hh17xDJYUHBZimVIt5fUyS8vbfpeSmTL3gUjTEvUV3qQ==",
 			"requires": {
 				"underscore": ">=1.8.3"
 			}
diff --git package.json package.json
index 4bf1a8435c..71a8b5e185 100644
--- package.json
+++ package.json
@@ -101,7 +101,7 @@
 		"@wordpress/url": "2.5.0",
 		"@wordpress/viewport": "2.3.0",
 		"@wordpress/wordcount": "2.2.0",
-		"backbone": "1.3.3",
+		"backbone": "1.4.0",
 		"clipboard": "2.0.4",
 		"element-closest": "^2.0.2",
 		"formdata-polyfill": "3.0.13",
diff --git src/js/media/controllers/state-machine.js src/js/media/controllers/state-machine.js
index 626f6c33ce..bb7fb31b27 100644
--- src/js/media/controllers/state-machine.js
+++ src/js/media/controllers/state-machine.js
@@ -14,17 +14,14 @@
  * @augments Backbone.Model
  * @mixin
  * @mixes Backbone.Events
- *
- * @param {Array} states
  */
-var StateMachine = function( states ) {
-	// @todo This is dead code. The states collection gets created in media.view.Frame._createStates.
-	this.states = new Backbone.Collection( states );
+var StateMachine = function() {
+	return {
+		// Use Backbone's self-propagating `extend` inheritance method.
+		extend: Backbone.Model.extend
+	};
 };
 
-// Use Backbone's self-propagating `extend` inheritance method.
-StateMachine.extend = Backbone.Model.extend;
-
 _.extend( StateMachine.prototype, Backbone.Events,/** @lends wp.media.controller.StateMachine.prototype */{
 	/**
 	 * Fetch a state.
diff --git src/js/media/views/attachment.js src/js/media/views/attachment.js
index 240f05c0ee..14d5e460db 100644
--- src/js/media/views/attachment.js
+++ src/js/media/views/attachment.js
@@ -66,7 +66,7 @@ Attachment = View.extend(/** @lends wp.media.view.Attachment.prototype */{
 			this.details( this.model, this.controller.state().get('selection') );
 		}
 
-		this.listenTo( this.controller, 'attachment:compat:waiting attachment:compat:ready', this.updateSave );
+		this.listenTo( this.controller.states, 'attachment:compat:waiting attachment:compat:ready', this.updateSave );
 	},
 	/**
 	 * @returns {wp.media.view.Attachment} Returns itself to allow chaining
diff --git src/js/media/views/media-details.js src/js/media/views/media-details.js
index 4b9a7c1a0d..ae643a3941 100644
--- src/js/media/views/media-details.js
+++ src/js/media/views/media-details.js
@@ -19,7 +19,7 @@ MediaDetails = AttachmentDisplay.extend(/** @lends wp.media.view.MediaDetails.pr
 	initialize: function() {
 		_.bindAll(this, 'success');
 		this.players = [];
-		this.listenTo( this.controller, 'close', wp.media.mixin.unsetPlayers );
+		this.listenTo( this.controller.states, 'close', wp.media.mixin.unsetPlayers );
 		this.on( 'ready', this.setPlayer );
 		this.on( 'media:setting:remove', wp.media.mixin.unsetPlayers, this );
 		this.on( 'media:setting:remove', this.render );
diff --git src/wp-includes/class-wp-user-query.php src/wp-includes/class-wp-user-query.php
index cde7811c88..64776e10e8 100644
--- src/wp-includes/class-wp-user-query.php
+++ src/wp-includes/class-wp-user-query.php
@@ -159,9 +159,8 @@ class WP_User_Query {
 	 *     @type string       $search              Search keyword. Searches for possible string matches on columns.
 	 *                                             When `$search_columns` is left empty, it tries to determine which
 	 *                                             column to search in based on search string. Default empty.
-	 *     @type array        $search_columns      Array of column names to be searched. Accepts 'ID', 'user_login',
-	 *                                             'user_email', 'user_url', 'user_nicename', 'display_name'.
-	 *                                             Default empty array.
+	 *     @type array        $search_columns      Array of column names to be searched. Accepts 'ID', 'login',
+	 *                                             'nicename', 'email', 'url'. Default empty array.
 	 *     @type string|array $orderby             Field(s) to sort the retrieved users by. May be a single value,
 	 *                                             an array of values, or a multi-dimensional array with fields as
 	 *                                             keys and orders ('ASC' or 'DESC') as values. Accepted values are
@@ -538,8 +537,8 @@ class WP_User_Query {
 			/**
 			 * Filters the columns to search in a WP_User_Query search.
 			 *
-			 * The default columns depend on the search term, and include 'ID', 'user_login',
-			 * 'user_email', 'user_url', 'user_nicename', and 'display_name'.
+			 * The default columns depend on the search term, and include 'user_email',
+			 * 'user_login', 'ID', 'user_url', 'display_name', and 'user_nicename'.
 			 *
 			 * @since 3.6.0
 			 *
diff --git src/wp-includes/script-loader.php src/wp-includes/script-loader.php
index 5366bfbcd0..eeb76639a7 100644
--- src/wp-includes/script-loader.php
+++ src/wp-includes/script-loader.php
@@ -1170,7 +1170,7 @@ function wp_default_scripts( &$scripts ) {
 	did_action( 'init' ) && $scripts->add_data( 'json2', 'conditional', 'lt IE 8' );
 
 	$scripts->add( 'underscore', "/wp-includes/js/underscore$dev_suffix.js", array(), '1.8.3', 1 );
-	$scripts->add( 'backbone', "/wp-includes/js/backbone$dev_suffix.js", array( 'underscore', 'jquery' ), '1.2.3', 1 );
+	$scripts->add( 'backbone', "/wp-includes/js/backbone$dev_suffix.js", array( 'underscore', 'jquery' ), '1.4.0', 1 );
 
 	$scripts->add( 'wp-util', "/wp-includes/js/wp-util$suffix.js", array( 'underscore', 'jquery' ), false, 1 );
 	did_action( 'init' ) && $scripts->localize(