diff --git a/src/wp-admin/includes/class-automatic-upgrader-skin.php b/src/wp-admin/includes/class-automatic-upgrader-skin.php
index 439fe597f1..a0126ecbde 100644
--- a/src/wp-admin/includes/class-automatic-upgrader-skin.php
+++ b/src/wp-admin/includes/class-automatic-upgrader-skin.php
@@ -14,6 +14,7 @@
  * is captured and stored for the caller to process and log/email/discard.
  *
  * @since 3.7.0
+ * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader-skins.php.
  */
 class Automatic_Upgrader_Skin extends WP_Upgrader_Skin {
 	protected $messages = array();
diff --git a/src/wp-admin/includes/class-bulk-plugin-upgrader-skin.php b/src/wp-admin/includes/class-bulk-plugin-upgrader-skin.php
index 498b55d535..f680273a54 100644
--- a/src/wp-admin/includes/class-bulk-plugin-upgrader-skin.php
+++ b/src/wp-admin/includes/class-bulk-plugin-upgrader-skin.php
@@ -11,6 +11,7 @@
  * Bulk Plugin Upgrader Skin for WordPress Plugin Upgrades.
  *
  * @since 3.0.0
+ * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader-skins.php.
  */
 class Bulk_Plugin_Upgrader_Skin extends Bulk_Upgrader_Skin {
 	public $plugin_info = array(); // Plugin_Upgrader::bulk() will fill this in.
diff --git a/src/wp-admin/includes/class-bulk-theme-upgrader-skin.php b/src/wp-admin/includes/class-bulk-theme-upgrader-skin.php
index 645482fc9a..b7a1256cb2 100644
--- a/src/wp-admin/includes/class-bulk-theme-upgrader-skin.php
+++ b/src/wp-admin/includes/class-bulk-theme-upgrader-skin.php
@@ -11,6 +11,7 @@
  * Bulk Theme Upgrader Skin for WordPress Theme Upgrades.
  *
  * @since 3.0.0
+ * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader-skins.php.
  */
 class Bulk_Theme_Upgrader_Skin extends Bulk_Upgrader_Skin {
 	public $theme_info = array(); // Theme_Upgrader::bulk() will fill this in.
diff --git a/src/wp-admin/includes/class-bulk-upgrader-skin.php b/src/wp-admin/includes/class-bulk-upgrader-skin.php
index 4b1de92d79..df78c34611 100644
--- a/src/wp-admin/includes/class-bulk-upgrader-skin.php
+++ b/src/wp-admin/includes/class-bulk-upgrader-skin.php
@@ -11,6 +11,7 @@
  * Generic Bulk Upgrader Skin for WordPress Upgrades.
  *
  * @since 3.0.0
+ * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader-skins.php.
  */
 class Bulk_Upgrader_Skin extends WP_Upgrader_Skin {
 	public $in_loop = false;
diff --git a/src/wp-admin/includes/class-core-upgrader.php b/src/wp-admin/includes/class-core-upgrader.php
index 0a7e43363b..2ff2fb1c79 100644
--- a/src/wp-admin/includes/class-core-upgrader.php
+++ b/src/wp-admin/includes/class-core-upgrader.php
@@ -14,6 +14,7 @@
  * the wp-admin/includes/update-core.php file.
  *
  * @since 2.8.0
+ * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader.php.
  *
  * @see WP_Upgrader
  */
diff --git a/src/wp-admin/includes/class-file-upload-upgrader.php b/src/wp-admin/includes/class-file-upload-upgrader.php
index d9e40063b4..35baa7faeb 100644
--- a/src/wp-admin/includes/class-file-upload-upgrader.php
+++ b/src/wp-admin/includes/class-file-upload-upgrader.php
@@ -14,6 +14,7 @@
  * to the Upgrade/Installer functions.
  *
  * @since 2.8.0
+ * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader.php.
  */
 class File_Upload_Upgrader {
 
diff --git a/src/wp-admin/includes/class-language-pack-upgrader-skin.php b/src/wp-admin/includes/class-language-pack-upgrader-skin.php
index 827d93f338..d368844ede 100644
--- a/src/wp-admin/includes/class-language-pack-upgrader-skin.php
+++ b/src/wp-admin/includes/class-language-pack-upgrader-skin.php
@@ -11,6 +11,7 @@
  * Translation Upgrader Skin for WordPress Translation Upgrades.
  *
  * @since 3.7.0
+ * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader-skins.php.
  */
 class Language_Pack_Upgrader_Skin extends WP_Upgrader_Skin {
 	public $language_update = null;
diff --git a/src/wp-admin/includes/class-language-pack-upgrader.php b/src/wp-admin/includes/class-language-pack-upgrader.php
index ad3aa30833..04ba25a333 100644
--- a/src/wp-admin/includes/class-language-pack-upgrader.php
+++ b/src/wp-admin/includes/class-language-pack-upgrader.php
@@ -12,6 +12,7 @@
  * for plugins, themes, and core.
  *
  * @since 3.7.0
+ * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader.php.
  *
  * @see WP_Upgrader
  */
diff --git a/src/wp-admin/includes/class-plugin-installer-skin.php b/src/wp-admin/includes/class-plugin-installer-skin.php
index 1579927cd9..a6df939a4b 100644
--- a/src/wp-admin/includes/class-plugin-installer-skin.php
+++ b/src/wp-admin/includes/class-plugin-installer-skin.php
@@ -11,6 +11,7 @@
  * Plugin Installer Skin for WordPress Plugin Installer.
  *
  * @since 2.8.0
+ * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader-skins.php.
  */
 class Plugin_Installer_Skin extends WP_Upgrader_Skin {
 	public $api;
diff --git a/src/wp-admin/includes/class-plugin-upgrader-skin.php b/src/wp-admin/includes/class-plugin-upgrader-skin.php
index 6782fc531d..cdb0b225db 100644
--- a/src/wp-admin/includes/class-plugin-upgrader-skin.php
+++ b/src/wp-admin/includes/class-plugin-upgrader-skin.php
@@ -11,6 +11,7 @@
  * Plugin Upgrader Skin for WordPress Plugin Upgrades.
  *
  * @since 2.8.0
+ * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader-skins.php.
  */
 class Plugin_Upgrader_Skin extends WP_Upgrader_Skin {
 	public $plugin = '';
diff --git a/src/wp-admin/includes/class-plugin-upgrader.php b/src/wp-admin/includes/class-plugin-upgrader.php
index e2d9308d24..ffb46204f2 100644
--- a/src/wp-admin/includes/class-plugin-upgrader.php
+++ b/src/wp-admin/includes/class-plugin-upgrader.php
@@ -14,6 +14,7 @@
  * or uploaded zip file.
  *
  * @since 2.8.0
+ * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader.php.
  *
  * @see WP_Upgrader
  */
diff --git a/src/wp-admin/includes/class-theme-installer-skin.php b/src/wp-admin/includes/class-theme-installer-skin.php
index 0dca21bc3f..c244fbb0ac 100644
--- a/src/wp-admin/includes/class-theme-installer-skin.php
+++ b/src/wp-admin/includes/class-theme-installer-skin.php
@@ -11,6 +11,7 @@
  * Theme Installer Skin for the WordPress Theme Installer.
  *
  * @since 2.8.0
+ * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader-skins.php.
  */
 class Theme_Installer_Skin extends WP_Upgrader_Skin {
 	public $api;
diff --git a/src/wp-admin/includes/class-theme-upgrader-skin.php b/src/wp-admin/includes/class-theme-upgrader-skin.php
index 70650d3cbe..1c98b7cc38 100644
--- a/src/wp-admin/includes/class-theme-upgrader-skin.php
+++ b/src/wp-admin/includes/class-theme-upgrader-skin.php
@@ -11,6 +11,7 @@
  * Theme Upgrader Skin for WordPress Theme Upgrades.
  *
  * @since 2.8.0
+ * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader-skins.php.
  */
 class Theme_Upgrader_Skin extends WP_Upgrader_Skin {
 	public $theme = '';
diff --git a/src/wp-admin/includes/class-theme-upgrader.php b/src/wp-admin/includes/class-theme-upgrader.php
index 8a49476d03..76129e3409 100644
--- a/src/wp-admin/includes/class-theme-upgrader.php
+++ b/src/wp-admin/includes/class-theme-upgrader.php
@@ -14,6 +14,7 @@
  * or uploaded zip file.
  *
  * @since 2.8.0
+ * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader.php.
  *
  * @see WP_Upgrader
  */
diff --git a/src/wp-admin/includes/class-wp-automatic-upgrader.php b/src/wp-admin/includes/class-wp-automatic-upgrader.php
index fcbb2603f7..098f992132 100644
--- a/src/wp-admin/includes/class-wp-automatic-upgrader.php
+++ b/src/wp-admin/includes/class-wp-automatic-upgrader.php
@@ -11,6 +11,7 @@
  * Core class used for handling automatic background updates.
  *
  * @since 3.7.0
+ * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader.php.
  */
 class WP_Automatic_Updater {
 
diff --git a/src/wp-admin/includes/class-wp-upgrader-skin.php b/src/wp-admin/includes/class-wp-upgrader-skin.php
index f1e04c62b7..e75ff16675 100644
--- a/src/wp-admin/includes/class-wp-upgrader-skin.php
+++ b/src/wp-admin/includes/class-wp-upgrader-skin.php
@@ -11,6 +11,7 @@
  * Generic Skin for the WordPress Upgrader classes. This skin is designed to be extended for specific purposes.
  *
  * @since 2.8.0
+ * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader-skins.php.
  */
 class WP_Upgrader_Skin {