You were a step ahead of me. After following the instructions in this thread

http://openacs.org/forums/message-view?message_id=154759

and running this query

insert into search_observer_queue(select revision_id, current_timestamp,\
'INSERT' from cr_revisions r,cr_items i where r.item_id=i.item_id and i.content_ty\
pe='etp_page_revision' and r.revision_id = i.live_revision);
INSERT 0 42


I now have the same error you do.