I’m also facing the same error in BP_XProfile_Field.
When i activate the bbpress themes wp-signup page is blank whereas on activating default WPMU theme i faced the
Fatal error: Call to undefined method BP_XProfile_Field::get_edit_html() in /home/dj/public_html/buzz/wp-content/plugins/buddypress/bp-xprofile/deprecated/bp-xprofile-deprecated.php on line 446
