Installing an Older WordPress Version
We all appreciate the fact that WordPress is constantly working to improve their product. However, sometimes a newer WordPress version does not seem compatible with a vital plugin. I recently had this experience myself with the release of WordPress 2.8. A plugin absolutely essential to my blog project would not operate in 2.8. I know the WP folks work hard to test with various plugins, but with 5,821 plugins available from WordPress,org and many more available elsewhere, they can’t check them all. Many great plug-ins were designed for a particular WordPress version and and basically abandoned by the author. Yet it may still work fine in that version.
The answer is to install an older version. You can download any past version of WordPress from the WordPress.org Release Archive. Then you can simply install it in the normal manner. You won’t be able to use Fantastico or one of the other automated installation systems, though. It is easy enough to install WordPress manually, though. Just check one of the many manual install tutorials, such as WordPress’ own.
If you’ve already upgraded and want to downgrade, it’s a bit trickier. The surest way is to delete the current version, then reinstall with the older version. First, back up your database (refer to this tutorial). As a precautionary measure, I like to regular make a copy of my blogs’ XML file, too, which could be used to restore the blog if the database somehow fails. You can do this in the Admin Dashboard at Tools>Export. Next, use a FTP client to delete all the blog files and folders, then upload the earlier version. During install, point WordPress to the previously used database as explained in this tutorial.