As stated in the title, my 404 template in WordPress does not show up every time a non-existent URL is accessed in my site. The page works perfectly in FireFox and Chrome, though. So I made a quick search and found that the solution is to add another header information in the page. So here’s what to insert at the very start of 404.php.
<?php ob_start(); ?>
<?php header("HTTP/1.1 404 Not Found"); ?>
For this, credit goes to wpcanada.
This is also touched in weblogtoolscollection.com at http://weblogtoolscollection.com/archives/2004/07/31/gzip-compression-issue-in-wordpress-12-mingus/
Note: ob_start() is a PHP function Turn on output buffering… whatever that means. 😀