Having upgraded from WPMU, there were problems since our blog, MHS Blog and Staff Blog, jumped to 3.x series. The biggest problem is when we jumped into 3.1. The Network Admin is no longer accessible. It always redirects us to “/wp-admin/network/” not “/admin/wp-admin/network/” even when we tried to set the address manually.
A temporary fix was to set “PATH_CURRENT_SITE” from “/” to “/admin/”. That could only enabling the Network Admin. But, all of the other user blogs became unaccessible. So, I have to set back and forth just to switch to maintenance mode or operational.
The real solution however is to set your admin blog (usually blog id “1”) to “/”. Apparently, the problem was because the Network Admin section searched for “/” path. While, we the relic from WPMU uses “/admin/” path in our main blog.
So, in wp_blogs table, we change the path of blogid 1 from “/admin/” to “/”. It works.
Btw, thx char101 for the solution. 🙂