How to Enable WordPress MU in WordPress 3.0

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One of the major changes to WordPress in version 3.0 is the merging of the blogging platform with its Multi User counterpart (WordPress MU). In a nutshell, WordPress MU allows multiple blogs to be set up under a single domain. Indeed, WordPress.com itself uses MU to give people a free blog.

In this post I will show you how to activate MU in the recently released version of WordPress.

Why Use MU?

The obvious question is; why use MU instead of just installing WordPress on multiple sites? Well, the sheer volume of work involved in setting up and configuring multiple blogs for one thing. With MU, it’s one installation, one setup.

Another consideration to make: a single installation of MU takes up far less hosting space than multiple installations of “vanilla” WordPress. Sure hosting is cheap these days, but it’s always nice to save space where possible.

Note however, that if having a unique domain name for each blog is important to you, then sadly MU is not for you.

However, if you run, or want to run:

a blog network
a newspaper/magazine
a University/school website
a web development company building custom sites using WordPress
any networked website

Then WordPress MU is probably the best tool for you.

How to Enable MU in WordPress 3.0

What you will need:

A WordPress 3.0 blog. This will not work with WordPress 2.x
Access to your hosting account via FTP or SSH

Step 1. By default, the menu option for MU is disabled. In order to activate it, you will need to add the following line to your wp-config.php file:
define('WP_ALLOW_MULTISITE', true);
I suggest you put it just before the line that reads: /* That’s all, stop editing! Happy blogging. */

Upload the file.

When you log in to (or reload) the admin interface on your blog, you will find a new option under ‘Tools’ titled ‘Network’. Go ahead and click it.

Step 2. WordPress is now going to ask you some questions in order to setup your “Network of WordPress Sites”. Take your time to read everything carefully. Pay particular attention to the network details where you choose a sub-domain or sub-directory structure. This option cannot be changed later.

Once you are happy, click ‘Install’.

Step 3. Next you will be told how to enable your blog network. Again, I highly recommend you read everything carefully. I also urge you to back up your current wp-config.php and .htaccess files – you really don’t want to have to reinstall WordPress if things go wrong.

You may or may not get any notice about missing authentication keys. I did, even though my config file already had them. I went ahead and added the new ones to the file rather than replace the existing ones. Everything seems to be fine so far.

As prompted at the bottom of this form, once you are done, log in again.

Step 4. Revel in the glory of your new status as Super Admin!