BuddyPress.org

Well, it seems like you have an issue, alright. Let’s go down the list once again:

1. You’re working with a current trunk of both WPMU 2.7.1_beta1 (current: r1725) and BuddyPress 1.0_RC2 (current: r1324)
2. You’re using an old copy of wp-config.php which you updated as appropriate. In other words, you did not use the wp-config-sample.php that came with WPMU 2.7.1.
3. You did a clean install of WPMU 2.7.1_beta1 by deleting everything, except your updated version of wp-config.php, and then uploaded the unzipped Mu files
4. You then launched WPMU’s admin screen. That worked with out any problems.
5. You then went to Site Admin > Upgrade and finished the upgrade
6. You logged out of WPMU
7. Next, you installed BuddyPress by:

• moving the contents of the unzipped BuddyPress 1.0_RC2 (r1324) to the WPMU plugins directory into a subdirectory called /buddypress/
• moving the /bp-themes/ directory out of the /buddypress/ directory
• placing the various themes in their proper locations

8. You then logged back into WPMU and got a blank screen

A few follow up questions:

9. You’ve enabled error reporting as detailed above by John and Burt and after step 8 above, there are absolutely no errors being reported of any kind.

A few thoughts:

• Since this seems to be a test install and you do not have any content that needs saving, I would delete everything once again.
• This also means deleting your MySQL table that you’ve been using for this attempt and starting with a brand new database.
• I would then download the latest trunks of both WPMU and BuddyPress once again–>get rid of the old ones first.
• I would then use the wp-config-sample.php file that comes with the latest WPMU trunk and configure as necessary
• IMPORTANT: I believe when I downloaded the WPMU trunk (r1722) and looked at the wp-config-sample.php file, it had a trailing space after the closing php tag. You need to delete this!
• Now, go through steps 1 through 7 again and let’s hope when you get to step 8 it works!