Index: wp-content/themes/twentyeleven/functions.php
===================================================================
--- wp-content/themes/twentyeleven/functions.php	(revision 44878)
+++ wp-content/themes/twentyeleven/functions.php	(working copy)
@@ -881,3 +881,21 @@
 	return $args;
 }
 add_filter( 'widget_tag_cloud_args', 'twentyeleven_widget_tag_cloud_args' );
+
+if ( ! function_exists( 'wp_body_open' ) ) :
+	/**
+	 * Fire the wp_body_open action.
+	 *
+	 * Added for backwards compatibility to support pre 5.2.0 WordPress versions.
+	 *
+	 * @since Twenty Eleven 3.3
+	 */
+	function wp_body_open() {
+		/**
+		 * Triggered after the opening <body> tag.
+		 *
+		 * @since Twenty Eleven 3.3
+		 */
+		do_action( 'wp_body_open' );
+	}
+endif;
Index: wp-content/themes/twentyfifteen/inc/template-tags.php
===================================================================
--- wp-content/themes/twentyfifteen/inc/template-tags.php	(revision 44878)
+++ wp-content/themes/twentyfifteen/inc/template-tags.php	(working copy)
@@ -267,3 +267,21 @@
 		}
 	}
 endif;
+
+if ( ! function_exists( 'wp_body_open' ) ) :
+	/**
+	 * Fire the wp_body_open action.
+	 *
+	 * Added for backwards compatibility to support pre 5.2.0 WordPress versions.
+	 *
+	 * @since Twenty Fifteen 2.5
+	 */
+	function wp_body_open() {
+		/**
+		 * Triggered after the opening <body> tag.
+		 *
+		 * @since Twenty Fifteen 2.5
+		 */
+		do_action( 'wp_body_open' );
+	}
+endif;
Index: wp-content/themes/twentyfourteen/inc/template-tags.php
===================================================================
--- wp-content/themes/twentyfourteen/inc/template-tags.php	(revision 44878)
+++ wp-content/themes/twentyfourteen/inc/template-tags.php	(working copy)
@@ -232,3 +232,21 @@
 	}
 	add_filter( 'excerpt_more', 'twentyfourteen_excerpt_more' );
 endif;
+
+if ( ! function_exists( 'wp_body_open' ) ) :
+	/**
+	 * Fire the wp_body_open action.
+	 *
+	 * Added for backwards compatibility to support pre 5.2.0 WordPress versions.
+	 *
+	 * @since Twenty Fourteen 2.7
+	 */
+	function wp_body_open() {
+		/**
+		 * Triggered after the opening <body> tag.
+		 *
+		 * @since Twenty Fourteen 2.7
+		 */
+		do_action( 'wp_body_open' );
+	}
+endif;
Index: wp-content/themes/twentynineteen/inc/template-tags.php
===================================================================
--- wp-content/themes/twentynineteen/inc/template-tags.php	(revision 44878)
+++ wp-content/themes/twentynineteen/inc/template-tags.php	(working copy)
@@ -238,3 +238,21 @@
 		);
 	}
 endif;
+
+if ( ! function_exists( 'wp_body_open' ) ) :
+	/**
+	 * Fire the wp_body_open action.
+	 *
+	 * Added for backwards compatibility to support pre 5.2.0 WordPress versions.
+	 *
+	 * @since Twenty Nineteen 1.4
+	 */
+	function wp_body_open() {
+		/**
+		 * Triggered after the opening <body> tag.
+		 *
+		 * @since Twenty Nineteen 1.4
+		 */
+		do_action( 'wp_body_open' );
+	}
+endif;
Index: wp-content/themes/twentyseventeen/inc/template-tags.php
===================================================================
--- wp-content/themes/twentyseventeen/inc/template-tags.php	(revision 44878)
+++ wp-content/themes/twentyseventeen/inc/template-tags.php	(working copy)
@@ -198,3 +198,21 @@
 }
 add_action( 'edit_category', 'twentyseventeen_category_transient_flusher' );
 add_action( 'save_post', 'twentyseventeen_category_transient_flusher' );
+
+if ( ! function_exists( 'wp_body_open' ) ) :
+	/**
+	 * Fire the wp_body_open action.
+	 *
+	 * Added for backwards compatibility to support pre 5.2.0 WordPress versions.
+	 *
+	 * @since Twenty Seventeen 2.2
+	 */
+	function wp_body_open() {
+		/**
+		 * Triggered after the opening <body> tag.
+		 *
+		 * @since Twenty Seventeen 2.2
+		 */
+		do_action( 'wp_body_open' );
+	}
+endif;
Index: wp-content/themes/twentysixteen/inc/template-tags.php
===================================================================
--- wp-content/themes/twentysixteen/inc/template-tags.php	(revision 44878)
+++ wp-content/themes/twentysixteen/inc/template-tags.php	(working copy)
@@ -264,3 +264,21 @@
 		}
 	}
 endif;
+
+if ( ! function_exists( 'wp_body_open' ) ) :
+	/**
+	 * Fire the wp_body_open action.
+	 *
+	 * Added for backwards compatibility to support pre 5.2.0 WordPress versions.
+	 *
+	 * @since Twenty Sixteen 2.0
+	 */
+	function wp_body_open() {
+		/**
+		 * Triggered after the opening <body> tag.
+		 *
+		 * @since Twenty Sixteen 2.0
+		 */
+		do_action( 'wp_body_open' );
+	}
+endif;
Index: wp-content/themes/twentyten/functions.php
===================================================================
--- wp-content/themes/twentyten/functions.php	(revision 44878)
+++ wp-content/themes/twentyten/functions.php	(working copy)
@@ -716,4 +716,20 @@
 }
 add_action( 'enqueue_block_editor_assets', 'twentyten_block_editor_styles' );
 
-
+if ( ! function_exists( 'wp_body_open' ) ) :
+	/**
+	 * Fire the wp_body_open action.
+	 *
+	 * Added for backwards compatibility to support pre 5.2.0 WordPress versions.
+	 *
+	 * @since Twenty Ten 2.9
+	 */
+	function wp_body_open() {
+		/**
+		 * Triggered after the opening <body> tag.
+		 *
+		 * @since Twenty Ten 2.9
+		 */
+		do_action( 'wp_body_open' );
+	}
+endif;
Index: wp-content/themes/twentythirteen/functions.php
===================================================================
--- wp-content/themes/twentythirteen/functions.php	(revision 44878)
+++ wp-content/themes/twentythirteen/functions.php	(working copy)
@@ -777,3 +777,21 @@
 	return $args;
 }
 add_filter( 'widget_tag_cloud_args', 'twentythirteen_widget_tag_cloud_args' );
+
+if ( ! function_exists( 'wp_body_open' ) ) :
+	/**
+	 * Fire the wp_body_open action.
+	 *
+	 * Added for backwards compatibility to support pre 5.2.0 WordPress versions.
+	 *
+	 * @since Twenty Thirteen 2.8
+	 */
+	function wp_body_open() {
+		/**
+		 * Triggered after the opening <body> tag.
+		 *
+		 * @since Twenty Thirteen 2.8
+		 */
+		do_action( 'wp_body_open' );
+	}
+endif;
Index: wp-content/themes/twentytwelve/functions.php
===================================================================
--- wp-content/themes/twentytwelve/functions.php	(revision 44878)
+++ wp-content/themes/twentytwelve/functions.php	(working copy)
@@ -665,7 +665,6 @@
 }
 add_action( 'customize_preview_init', 'twentytwelve_customize_preview_js' );
 
-
 /**
  * Modifies tag cloud widget arguments to display all tags in the same font size
  * and use list format for better accessibility.
@@ -684,3 +683,21 @@
 	return $args;
 }
 add_filter( 'widget_tag_cloud_args', 'twentytwelve_widget_tag_cloud_args' );
+
+if ( ! function_exists( 'wp_body_open' ) ) :
+	/**
+	 * Fire the wp_body_open action.
+	 *
+	 * Added for backwards compatibility to support pre 5.2.0 WordPress versions.
+	 *
+	 * @since Twenty Twelve 3.0
+	 */
+	function wp_body_open() {
+		/**
+		 * Triggered after the opening <body> tag.
+		 *
+		 * @since Twenty Twelve 3.0
+		 */
+		do_action( 'wp_body_open' );
+	}
+endif;
