[wp-hackers] WPMU Category ID Updating

Brian Layman Brian at TheCodeCave.com
Thu Jan 28 16:58:15 UTC 2010

(If Tim Schoffelman is around, this also answers his December question of "
[wp-hackers] WordPress MU Category Slugs: Was/is there a reason why
WordPress MU doesn't allow category slugs to be edited?")

There is code in WPmu that is there to further some non-standard features
(re: the whole site-category table). When importing all of the b5media sites
into MU, I had to disable all of that because it has some fundamental flaws.
Mark Jaquith and I spent hours going over the code and decided that
disabling it was the ideal solution. It does exactly what you have been

In short, there is an attempt to keep all slugs matching the category name
and to have all categories use the same IDs across the board. However, the
matching of slug and category conflicts with pre-existing imports and you
will very quickly find your Google 404s cranking up as your permalinks
change.  Additionally, because tags and cats both get term IDs and only
category ids are synchronized between blogs, collisions between
site-categories and individual blog term tables are quite likely. At that
point, you get key violations that aren't handled well by the editor
displayed only as "Cannot edit" or something along those lines.

I've disable both of these mu customizations with a plugin that has these
remove_filter ( 'term_id_filter', 'global_terms', 10, 2 ); 
remove_filter( 'get_term', 'sync_category_tag_slugs', 10, 2 );

YMMV, but I think this is what you are seeing.

This is the exact text I'd sent to reply to the thread "WordPress MU
Category Slugs" from back in December, but that post never made it to the

- Brian Layman

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