Categories/Tags links are broken in WP 3.3.1, with multisite/subfolder install

[tszming]

All the default categories/tags links are not working, showing error..

"This is somewhat embarrassing, isn’t it?"

Steps to reproduce:

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1. Install WP 3.3.1 on domain, e.g. ​http://blog.example.com
2. Enable multi-site features, using subfolder instead of subdomain
3. Create a site, e.g. ​http://blog.example.com/test1
4. Create a post, e.g. ​http://blog.example.com/test1/2012/03/04/test1/
5. Enter the default category link, e.g. ​http://blog.example.com/test1/category/uncategorized/

Now you will see the message: "This is somewhat embarrassing, isn’t it?"

Fix:

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1. Enter this link: ​http://blog.example.com/test1/wp-admin/options-permalink.php
2. Change nothing, press "Save Changes"
3. Now you can view the link correctly: ​http://blog.example.com/test1/category/uncategorized/

The above issue also apply to tags

Seems like the permalinks are not flushed when creating a site.

Rewrite rules are flushed during site creation, see wp_install_defaults().

The problem is that categories, tags and formats have already been registered with the "/blog/" prefix because they were registered during the init of the main site. So, when the rewrite rules are generated they have a different structure to the rest of the rules. I suspect that you encounter the same problem for any custom taxonomies/post types which register with_front as true.

In 3.1 it was only formats that had the problem. with_front => true was introduced for categories and tags in 3.1.1.

I thought of maybe adding a "rewrite_init" action to WP_Rewrite::init() and hooking taxonomy registration onto that. So taxonomies are re-registered whenever the permalink structure is changed.

'rewrite_init' seems like a good idea. Any drawbacks to using it for general CPT and taxonomy registration?

Replying to scribu:

'rewrite_init' seems like a good idea. Any drawbacks to using it for general CPT and taxonomy registration?

None that I have found so far.

Related #20174.