I have a WPMU site with hundreds of blogs on it. We are on 3.4.2 and this is the first time I'm seeing this issue within a few of my sites.

Basically, what happens is that I'll create a new category and then when I click on it from the sidebar where all the categories appear, it 404's. Also, this happens when I add a new article to the new category.

This is happening on a few of my sites now. What's interesting to note is I cannot reproduce the issue on test even though test is more of less a direct clone of my live envrionment. The only difference between live and test is that I use a domain mapping plugin on live. Also, I have 6 memcached nodes/servers (AWS) whereas my test area only has one. My live area has 5 app servers and my test area has one. We have the multi-DB plugin installed in both environments. Aside from those differences, the plugins are exactly the same as is the code base.

The issue happens:

--> Regardless of category slug

--> Regardless of # posts assigned to the category

--> Only on newly created categories (we noticed it about a month ago and it's still happening -- and seems to be spreading across our network)

--> On the front end -- you can browse categories just fine on the back end.

--> Regardless of how many times I flush the rewrite rules by changing permalink settings

--> On any permalink setting other than default. If I go to default permalink structure, it works fine.

--> Only on categories -- tags work fine.

  • are you using a plugin like WP no category base or Yoast WordPress SEO option which removes category base?
    – Milo
    Jan 30, 2013 at 0:04
  • 1
    Yes. We are using the Yoast plugin. It was the first thing I checked. But it's not the cause in this case. I played enough with the strip category base option to confirm it's not the culprit. It turns out the culprit is 302 redirects not resolving on occasion. There's no real identifiable pattern. it's probably something with our cache.
    – yoyodyne
    Jan 30, 2013 at 23:02
  • What is your Permalink structure, and do you have any custom Taxonomies or Post Types? Feb 7, 2013 at 1:47
  • 1
    Did you disable all plugins and check? This is among the first things I'd do when I have no clue.
    – its_me
    Feb 7, 2013 at 13:13

1 Answer 1


In the interest of closure and so someone in the future researching anything similar doesn't get sidetracked by my posting here, it turned out to be our memcached. Once we hooked up to a new cache, the category issue disappeared.

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