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 ( 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!

Comments (26)

  1. Lester, it happens with every upgrade. It’s normal. Functions change and plugins have to be kept up and modified for those changes. (Not pointing figures. Being honest here.)

    It does make me scratch my head though knowing how long this has been in development. You would think that developers would be checking their products to make sure they work. Doesn’t always happen that way though.

    I know Aaron is but is anyone else waiting for 3.0.1? We are simply to give plugin developers the chance to play catch up.

  2. So, the /mu-plugins/ directory is still needed, we just need to get the updated versions of those plugins for those features to work with a pre-existing WPMU site under core WP 3.0? That’s good news; I was nervous about what was going to happen to the mu-specific mods & plugins after WPMU got integrated into core WP.

  3. It looks like I’m gonna love this new 3.0 WP version! I just ran it locally and it upgraded with all plugins (including the old ones) intact. There were no errors.

    Then I made another local install and the new menu system is excellent! Customizing and the order of menus is easier now. Bye2x plugin for that! This was always a problem for me with the original blog page always showing up so I ended up with 2 homes on the menu. lawl!

    w00t! Kudos WP team! :)

  4. After upgrading to WordPress 3.0 the import feature (import from blogspot, import from wordpress, etc.) doesn’t work any more. Is this a WordPress 3.0 bug or… ?

  5. Help please… WordPress import ( of XML file) is broken.

    I installed the plugin wordpress-importer and activated. When attempting to import, it loads a blank screen.

    • All our plugins have been updated to work with 3.0. You have to be a member to download updates. Of course if you are a member and find bugs you can report them in our forums and we’ll fix em up asap.

  6. Hi Aaron,

    Thanks for the great article. I have a question regarding the WP3 MultiSite’s network feature. In this post you touched on the “New Network” feature and mentioned that “Unless you are using a special plugin a MultiSite install only has one Network”

    I would like to know what plugin we can use to create more than 1 network in the WP3 MutiSite. Also will the users be able to use the same login info to visit all the sites in the networks (if we have the right plugin to create more than 1 network) and have different roles.

    Thank you,

  7. Hi,

    We use WordPress and Atahualpa 3.4.1 as a website and since updating to WordPress 3.0.1, the navigation bar has started to play up.

    A parent page with sub-menus doesn’t open to the right of the menu but below the menu causing problems to read the rest of the parent menu.

    To understand what I mean visit and hover over the navigation bar to resources and go down to budget report.

    As you will find the budget report sub-menus go down instead of appearing to the right. Any suggestions of how to fix this??

    Kind Regards