Ticket #39302: 39302.1.patch

src/wp-content/themes/twentyseventeen/header.php

@@ -41 +41 @@
         </header><!-- #masthead -->
 
         <?php
-        // If a regular post or page, and not the front page, show the featured image.
-        if ( has_post_thumbnail() && ( is_single() || ( is_page() && ! twentyseventeen_is_frontpage() ) ) ) :
+
+        /*
+         * If a regular post or page, and not the front page, show the featured image.
+         * Using get_queried_object_id() here since the $post global may not be set before a call to the_post().
+         */
+        if ( ( is_single() || ( is_page() && ! twentyseventeen_is_frontpage() ) ) && has_post_thumbnail( get_queried_object_id() ) ) :
                 echo '<div class="single-featured-image-header">';
-                the_post_thumbnail( 'twentyseventeen-featured-image' );
+                echo get_the_post_thumbnail( get_queried_object_id(), 'twentyseventeen-featured-image' );
                 echo '</div><!-- .single-featured-image-header -->';
         endif;
         ?>