So, as part of my GenEd work, I was asked to move a WordPress MU installation to a new server.  I found several articles about moving around standard WordPress installations, but nothing for the MU (MultiUser) version.  In particular, I had a hard time with changing the domain name.  In this article, I'll assume that you already know the general procedure (backing up your files and database, moving, and restoring).  All I plan on covering is how to change your installation's domain name.

  1. Make a text backup of your database.  You can do this by using something like mysqldump, phpMyAdmin, or the MySQL GUI Tools.
  2. Using your favorite tool, like notepad, sed, or any other text editor that can handle large files, replace all instances of your old domain name with your new one.
  3. Save this file and then import it into your database.
  4. In the root of your WordPress MU install, there should be a wp-config.php file.  The majority of this file is a series of DEFINE statements that define some settings.
  5. You should see a like like this:
    define('DOMAIN_CURRENT_SITE', ''); Replace it with: define('DOMAIN_CURRENT_SITE', ''); 
  6. For whatever reason, you'll get a register page if you attempt to visit your site.  To fix this, log in as admin and then log out.
  7. Done!

I hope this helps somebody.  Feel free to comment if you have questions, concerns, or corrections.

- bstempi