Comment 10 for bug 403381

Just to help some people out who ended up in this situation (if you "ignored" the debconf message):

I found a nice little example on how to repair this on http://www.tumblr.com/tagged/server+administration .

1. Stop cluster for 8.4, if it’s running:

    sudo pg_ctlcluster 8.4 main stop

2. Drop the cluster for 8.4

    sudo pg_dropcluster 8.4 main

3. With 8.3 running, run pg_upgradecluster

    sudo pg_upgradecluster -v 8.4 8.3 main

4. If all goes well, cluster for 8.3 can be dropped

    sudo pg_dropcluster 8.3 main

And we are probably back on track with PostgreSQL.