Important Things You Should Know Before Upgrading to WordPress 3.0

After more than 6 months of development, WordPress 3.0 is out! Many of you will be anxious to update right away, but there are some important things you should know first:WordPress 3.0

General Info

WordPress MU has been merged into regular WP, which means whether or not you need multiple blogs (sites now) you will download it from the same place (http://wordpress.org/download/). We will be updating our comprehensive manuals over the coming weeks with the new installation process. For now, check out our simple upgrade guide here: How to Upgrade WPMU 2.9.2 to WordPress 3.0 in 5 Easy Steps

New Terminology

Also it is important to know that much of the terminology we were used to in WPMU has changed, so to avoid confusion here is a quick glossary:

  • WordPress MU -> WordPress Multisite (or “MultiSite”, “MS”, etc. This is WP with MultiSite enabled)
  • Blog -> Site (a blog that a user can signup for)
  • Site -> Network (a group of blogs are tied together, usually with a main blog to head them up and accept registrations. Unless you are using a special plugin a MultiSite install only has one Network)
  • Site Admin -> Super Admin (the super user that has access to everything in the Network)
  • All the admin menu’s under “Super Admin” have also changed to reflect this new terminology.

Updating Plugins & Themes

Due to the vast amount of changes made in 3.0, many plugins and some themes will be broken unless they are updated to work with WP 3.0. This is especially true for WPMU plugins and BuddyPress themes. Almost every single one will be broken if you don’t update them. Luckily, if you are a member of WPMU DEV you have our upgrades guarantee, and we will have every single one of our plugins & themes compatible by the end of today!


When you update to 3.0, you will need to also update to the latest versions of WPMU DEV plugins and themes!
If you do not, there is a very good chance your site will be broken or even inaccessible until you do. It is also important to know that many of our WP 3.0 compatible plugin and theme versions WILL NOT be backwards compatible to WPMU 2.9.2 due to the vast changes between versions. If you are running WPMU 2.9.2 and want to install a plugin or theme from here you will need to go into the past versions and download an older one.

If you are doing a fresh install of WP 3.0 MultiSite there is a very important step to consider. The /wp-content/mu-plugins/ folder will no longer be created by default. Many MultiSite plugins will still need to be installed in this folder though. Simply create the /wp-content/mu-plugins/ folder if it doesn’t exist and follow the regular install instructions. We will be updating our documentation to reflect this fact soon.

Final Instructions

So in summary, when updating to WP 3.0, you will also have to update most all your plugins/themes, especially WPMU/BuddyPress ones at the same time. We HIGHLY recommend setting up a test install and upgrading that first to make sure everything works before upgrading a live site. It will save you and your user’s a lot of pain!

Happy Updating!