Minimum requirements: PHP 5 and Mysql 4.1
Be careful - many changes were made in styles, such as switching to a tableless design and revamping how buttons are styled. Many themes that were in the package are no longer supported (Please read Theme Issues when Updating to Tiki 3.0) Plan some time to update your style (see note below) if you are not ready to change it to a bundled one.

Review ReleaseNotes30.

From version to version, some behavior may change. Some features were not optional before and now are optional, such as wiki structures. You need to turn these on.

Read the instructions on how to make a Backup.

Get Tiki 3 from here: http://info.tikiwiki.org/Download

Upgrade process from 2.x to 3.0 is fairly easy, and it should be self-explanatory.

If you need further instructions, ask in Irc or in the tw forums: http://tikiwiki.org/forums, and please, come back here and upgrade the documentation to make it easier for new users with what you learned.

• If you are upgrading the site from an earlier Tiki release and you have these themes installed already - Darkroom, Feb12, TheNews, and Tikinewt - you must remove all the old files in their template directories (such as templates/styles/thenews/tiki.tpl). These old files are not compatible with Tiki 3. These four themes' template directories should contain only index.php and credits.tpl.
• Other pre-Tiki 3.0 themes are generally incompatible now, so will cause display and function problems. For an immediate fix at the site, switch to one of the new Tiki 3.0 themes.
• If your site uses a customized theme, you will need to make major adjustments. Themes based on old Tiki themes other than the four listed above will not work correctly in Tiki 3. In particular, header.tpl and tiki.tpl have been changed significantly, but there are other changes throughout the template files and stylesheets. If your left and right columns display below the middle column, this indicates that lite.css properties are missing, so this file needs to be imported (add @import "lite/lite.css"; at the top of your theme stylesheet). This CSS file handles the new tikiwiki tableless layout that is now the default method. In updating your styling, note that in this method, the left and right columns are div id="col2" and div id="col3", which are changed from td id="leftcolumn" and td id="rightcolumn" in the old default.
• Module title: the module title was in a div before;; now it is in an h3. You may need do add a h3.box-title in your stylesheet in place of div.box-title
• Perhaps the search module and the tikiwiki logo will appear at the top. You may tune this in admin->look, second tab
• The buttons have changed. Add something like .button a to the stylesheet in place of a.linkbut and set the margin to 0.
• If you have hard links to tiki-file_galleries.php you need to change to tiki-list_file_gallery.php.
• If you want a design with the classic "table" look (full-height borders and backgrounds on side and middle columns, etc.) then see Tiki 3-compatible table-using themes at mods.tikiwiki.org (or themes.tikiwiki.org) such as Kubrick or Andreas08 for use as models, if necessary.

More specifically, structures, search, individual plugins, and some other features may have to be activated in the admin panel.

Usage of potentially unsafe wiki plugins has to be validated by users with the new permissions related to approve plugins. This way, any usre can make any attempt to use potentially any plugin, including iframe, dbreport, tag, sql, snarf, regex... which would need to be validated by some trusted users/editors/admins later on in order to aprove or reject them.

A list of plugin calls pending revision can be found at any time here: tiki-plugins.php

You can read and learn about it at this page: Tiki3

• http://tikiwiki.org/ReleaseNotes30
• Upgrade