bbPress 0.9 requires WordPress 2.5 "out of the box" but I have just released a couple of plugins that allow for integration with earlier versions of WordPress (e.g. version 2.3).
Although you can use these plugins to get integration with earlier versions happening, it is still strongly recommended that you upgrade your WordPress installation to version 2.5!
Only follow this guide if you are using bbPress 0.9 or higher and are trying to integrate it with a WordPress installation with a version earlier than version 2.5!!!
The problem with using earlier versions of WordPress is two-fold:
- The password hashing algorithm has changed.
- The authentication cookie is now different.
The solution is to install these two plugins into bbPress:
- "MD5 Insecurity for bbPress" - downgrades bbPress' password hashing back to MD5.
- "Mouldy Old Cookies for bbPress" - Reinstates use of the old cookie styles in bbPress.
Download and install each of these into bbPress. No plugins should be necessary in WordPress to enable integration.
I recommend you make these plugins "autoload" by pre-pending an underscore "_" to the plugin filename. This means the plugins will always load and can't be deactivated from the plugin page in the admin area.