is_404() │ WP 1.5.0

Checks whether the 404 error page is displayed (HTTP 404: page not found). Conditional tag.

No Hooks.

Returns

true|false. Whether the query is a 404 error.

Usage

is_404();

Examples

0

#1 Determine if the current page is 404

If a theme template doesn't have 404.php file then you can add following code to single.php. 

if ( is_404() ) {        
	// you can add search form here          
	// so the user can find a needed post        
}

Notes

  • Global. WP_Query. $wp_query WordPress Query object.

Changelog

Since 1.5.0 Introduced.

is_404() code WP 7.0

wp-includes/query.php 
function is_404() {
	global $wp_query;

	if ( ! isset( $wp_query ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
		return false;
	}

	return $wp_query->is_404();
}

Conditional tags (page type and request)

Conditional tags (all)

Queries

Main Functions