Okay, at least I found out roughly whats happening: The buddypress legacy group forums (which I have since I started a community originally with buddypress 1.6x) is working fine in 1.8. However, newly created legacy group forums in 1.8 do give above error notice and the forums do not work at all.
Was this mentioned somewhere in the update notes? If not, it should be, because it created quite some trouble.
Even worse then is what I described above, that I can’t simply switch and convert to the new bbpress 2.3 group forums, since then all attachments are lost to normal user interface (and since we have several hundred documents attached, manually reassigning them somehow is not an option).
For now, I had to switch back to buddypress 1.7.3 where newly created groups have functioning forums and the attachments using U Forum Buddypress Attachments plugin are included.
I had a rough look at the sql database and can’t imagine an easy quick way to migrate attachments from U Forum Buddypress Attachments plugin to e.g. GD bppress attachments, which would work with bbpress 2.3 group forums.
Does anyone have a clue whether and how that would be possible in an automated way? Otherwise I can’t update buddypress without losing functionality of either creating new groups with working forums or losing all previous attachments in posts!
