There’s been a long-standing bug in WordPress 2.X, ever since WordPress switched to internal rewrites instead of external ones within .htaccess. The bug is that UltimateTagWarrior displays 404 errors (File Not Found) on tag pages when you have rewriting of local tag URLs turned on (in Options > Tags in the WordPress admin). The bug usually only manifests itself when you are using custom permalinks (i.e. if you’ve selected “Custom” from the Permalink Options in the WordPress admin).

Well I’ve got good news! I’ve figured out the problem!

Turns out when you have a Custom Permalink structure like /%postname%/ defined, then one of WordPress’ rewrite rules matches against /tag/whatever before the rewrite rules (which are at the end of the list) get a chance to be invoked. Here’s the offending rewrite rule that’s doing the hijacking:

[[^/]+/([^/]+)/?$] => index.php?attachment=$1

That rewrite rule is a bit too greedy!

I used the Internal Rewrite Viewer plugin to figure out what was going on. This Ultimate Tag Warrior bug been a source of frustration for months. Man, it was tricky to track this one down. It’s good to finally know what the issue is — and how it can be fixed!

Other plugins like WP-Print and WP-Email aren’t affected by this because their rules are the very top of the array instead of the bottom.

I’ve alerted Christine, the author of UTW. Hopefully she will come out with an updated version of the plugin soon to put the rules at the top of the array. If not, I’ll will fix the plugin myself and publish the hack here.

But what if you have a WordPress-powered site and you want to tag static Pages, not just Posts? Well I have some good news! Even though Ultimate Tag Warrior doesn’t currently support tagging of Pages, I managed to figure out a workaround. The hack (to version 3.14159 of the plugin) involves the addition of a mere two lines of code…

First, add after line 1551 of ultimate-tag-warrior-core.php:
$request = preg_replace("/ AND post_status != 'static'/","", $request);

Second, and add after line 819 on ultimate-tag-warrior-actions.php:
add_action('edit_page_form', array('UltimateTagWarriorActions','ultimate_display_tag_widget'));

The first line modifies the MySQL select statement that specifically excludes static pages.

The second line adds the tag field to the Write Page form.

I’ve communicated this hack to Christine Davis, the author of the UltimateTagWarrior plugin. Happily, she said she will look at adding it to the next version.

UPDATE: This hack has made it into the latest version of UTW. Unfortunately, the hack doesn’t work with WordPress 2.1. So if you’re running WP2.1, tagged static pages don’t show up on tag pages. That’s because the WordPress developers switched to using post_type = ‘page’ for static pages. So I got it working by putting the following into line 1564 in ultimate-tag-warrior-core.php (version 3.1415926 of UTW):
$request = preg_replace("/post_type = 'post'/","post_type = 'post' OR post_type = 'page'", $request);