diff --git src/wp-admin/includes/post.php src/wp-admin/includes/post.php
index c9b29b5df4..ed9456a51b 100644
--- src/wp-admin/includes/post.php
+++ src/wp-admin/includes/post.php
@@ -1435,7 +1435,7 @@ function get_sample_permalink( $id, $title = null, $name = null ) {
 	$post->post_status = $original_status;
 	$post->post_date   = $original_date;
 	$post->post_name   = $original_name;
-	unset( $post->filter );
+	$post->filter      = null;
 
 	/**
 	 * Filters the sample permalink.