BuddyPress.org

@quaker-oats (breakfast man ?)

1. I deactivated all plugins. OK

2. I first upgraded to WPMU 2.9.1 successfully. OK

3. Then I tried manually overwriting the old BP plugins folder, with the new BP 1.2 folder.

As written in the readme, it’s better you erase the old BP folders (after making a copy) before installing 1.2

To be sure that ALL files are the new one.

4. I then deleted the themes folder.

The theme folder belongs to WPMU, why did you erase it ?

BP 1.2 themes are in a bp-theme folder ans this folder doesn’t need to be moved, as by the past version.

WPMU now detect automatically the BP theme.