I’m getting an error all of a sudden to my code

function is_member_online($user_id, $time=5){
    global $wp, $wpdb;

    $user_login = $wpdb->get_var( $wpdb->prepare( "
        SELECT u.user_login FROM $wpdb->users u JOIN $wpdb->usermeta um ON um.user_id = u.ID
        WHERE     u.ID = $user_id
        AND um.meta_key = 'last_activity'
        AND DATE_ADD( um.meta_value, INTERVAL $time MINUTE ) >= UTC_TIMESTAMP()
        "
    ));
    if(isset($user_login) && $user_login !=""){
        return true;
    }
    else {return false;}
}

This checks if bbpress members are online. This is the error that is being resulted

Warning: Missing argument 2 for wpdb::prepare(), called in /hermes/bosweb/web172/b1721/ipg.dnbrawlercom/lsheroes/wp-content/themes/SaveLSHoooo/custom-functions.php on line 15 and defined in /hermes/bosweb/web172/b1721/ipg.dnbrawlercom/lsheroes/wp-includes/wp-db.php on line 992

It has been happening working until recently.

[@lynqoid Participant 10 years, 11 months ago]

The wpdb prepare uses a placeholder like %s and then replaces it with the first variable in the arguments after the query itself.

For example:

$user_login = $wpdb->get_var( $wpdb->prepare( 
	"SELECT u.user_login FROM $wpdb->users u JOIN $wpdb->usermeta um ON um.user_id = u.ID
        WHERE     u.ID = %s
        AND um.meta_key = 'last_activity'
        AND DATE_ADD( um.meta_value, INTERVAL %s MINUTE ) >= UTC_TIMESTAMP()
	", 
	$user_id, $time
) );

Good luck!