BuddyPress.org

I have been having the same issue and it looks like I might have a solution – I’ll at least post what steps I’ve taken and what documentation I based them on. I am running WordPress 3.5.1 as a multisite subdirectory installation on a WIMP server.

I read over this page of documentation that seems to apply to the situation, and I added the
define ( ‘BP_ROOT_BLOG’, # ) line to the wp-config.php file in the root directory.
https://codex.buddypress.org/user/install-buddypress-on-a-secondary-blog/

That didn’t solve it, so I went back to read over this page:
https://codex.buddypress.org/developer/customizing/changing-internal-configuration-settings/
I find the references to WPMU kind of confusing, since that hasn’t been used since before 3.0, I thought. And when I looked for the “bp-custom.php” file, I don’t see it anywhere in the recent installation. I found some of the same lines in the bp-loader.php file, but changes to that file didn’t change anything, since it seemed to be looking for a multiblog setting fist.

So I went to this page and read through it:
https://codex.buddypress.org/bp_enable_multiblog/
That lead me to add this line to my wp-config.php file:
define ( ‘BP_ENABLE_MULTIBLOG’, true );

I removed the changes I’d made to the bp-loader.php file to be sure there wouldn’t be problems later.

With both lines added to the wp-config.php file, I was finally able to go to this page and see the pages that belonged to the subsite rather than the root blog: {websiteurl}wp-admin/admin.php?page=bp-page-settings. I will need to check to see what changes this makes to the rest of my blogs, but at least we have a test site running Buddypress now.

Also, is there any chance these codex pages could get updated? There are all kinds of references to multisite or network or WMPU that are not entirely clear and, as I mention above, there are instructions to open files in the buddypress install that don’t exist by those names anymore.

I don’t really know the code that well to be sure I’m being accurate, though, especially if the codex is instructing people to make changes to core files.