We have a relatively new WP Multisite install (about a month old). As of recently, we're unable to add new blogs to our site. Or, I should say, we can add new blogs, but they're not being added correctly.
When I look at the database, the new entry is being added to wp_blogs, but I'm not seeing tables created with the corresponding blog_id (wp_X_commentmeta, wp_X_comments, wp_X_links, etc...). I've checked that the DB user I'm using has permission to create tables.
The "Create a Network" page in the CODEX has this about multisite installs:
You cannot choose Sub-directory Install in the following cases:
If your existing WordPress installation has been set up for more than a month, due to issues with existing permalinks. (This problem will be fixed in a future version.)
I'm not sure if this applies to my situation or not. I chose sub-directory install immediately after setting up the site. However, my site is now more than a month old. Does the sentence above mean that after a month you can't create new blogs on a Multisite install if you're using the subdirectory option? I'm having a hard time believing that this limitation exists in a stable release.