Change Related Blog Posts To Be Based on Tags

/**
 * Alter single posts related section to display related items based on tags and NOT categories
 *
 * @urlhttp://total.wpexplorer.com/docs/snippets/related-blog-posts-based-tags/
 *
 */
function myprefix_alter_related_posts_query_args( $args ) {

	// Remove category arguments
	$args['category__in'] = null;

	// Get post tags
	$tags = wp_get_post_terms( get_the_ID(), 'post_tag' );

	// If post has tags, create array of tag ids and query posts inside these tags
	if ( $tags ) {
		$tag_ids = array();
		foreach( $tags as $tag ) {
			$tag_ids[] = $tag->term_id;
		}
		$args['tag__in'] = $tag_ids;
	}

	// Return arguments
	return $args;

}
add_filter( 'wpex_blog_post_related_query_args', 'myprefix_alter_related_posts_query_args' );