I had just figured out my problem and was checking back on this thread.
I’m using Multi-DB and am putting the bbpress tables in the global database that Multi-DB requires. I also had to update BBDB_NAME to point to the global db. In this setup, the db settings in wp-config.php are being overriden apparently by db.php, db-config.php (Multi-DB). I only needed to update bb-config.php (for BBDB_NAME).
Even if one isn’t using the BlogsMU theme, it is possible that the same scenario I described in the link above could occur with an incorrect URL reference in another theme.
I’m wondering if it might be better/safer if BuddyPress avoided cookies altogether in the group creation process and instead relied on the URL to carry state information?
Here are a couple other posts related to “There was an error when creating the topic” that may or may not be relevant to a particular instance of the error.
I saw the exact same scenario as Anointed described in the first 2 messages of this thread. I tried to perform some experiments with fresh installs and believe I may have linked at least one of my issues to an interaction between BuddyPress and Multi-DB.
