Re: Help with Upgrading my Site
BP 1.0.2 is the last version compatible with MU 2.7.1.
If I were you, I’d wait for the next version of BuddyPress – version 1.1 scheduled to be released next week.
You would need to upgrade WPMU to 2.8.4.
When you upgrade, make sure you backup everything! (database, wp-content directory)
Deactivate all plugins, rename “mu-plugins” folder (if you use mu-plugins) and then install WPMU over your existing install.
Next, install new version of BuddyPress, reactivate plugins and everything should be good (I say should because each case is different!).
Since you didn’t mention bbPress, I presume you don’t have to worry about it, which is good, since that takes out one main item out of the equation!