Index: wp-content/themes/twentyfifteen/functions.php
===================================================================
--- wp-content/themes/twentyfifteen/functions.php	(revision 44933)
+++ wp-content/themes/twentyfifteen/functions.php	(working copy)
@@ -75,7 +75,7 @@
 		/*
 		 * Enable support for Post Thumbnails on posts and pages.
 		 *
-		 * See: https://codex.wordpress.org/Function_Reference/add_theme_support#Post_Thumbnails
+		 * See: https://developer.wordpress.org/reference/functions/add_theme_support/#Post_Thumbnails
 		 */
 		add_theme_support( 'post-thumbnails' );
 		set_post_thumbnail_size( 825, 510, true );
Index: wp-content/themes/twentysixteen/functions.php
===================================================================
--- wp-content/themes/twentysixteen/functions.php	(revision 44933)
+++ wp-content/themes/twentysixteen/functions.php	(working copy)
@@ -81,7 +81,7 @@
 		/*
 		 * Enable support for Post Thumbnails on posts and pages.
 		 *
-		 * @link https://codex.wordpress.org/Function_Reference/add_theme_support#Post_Thumbnails
+		 * @link https://developer.wordpress.org/reference/functions/add_theme_support/#Post_Thumbnails
 		 */
 		add_theme_support( 'post-thumbnails' );
 		set_post_thumbnail_size( 1200, 9999 );