Finally the upgrade was successful. Thanks goes out to Alexey Shchepin who could read the log files, and for those who does not know, he is also the main developer of ejabberd.
The upgrade problem was related to the fact that we earlier tested out a two node cluster, and now one node has been offline (terminated), thus removed uncleanly. Even if the node was removed it still existed in the database, and needed to be cleaned manually before the upgrade.ÃÂ I have been looking for information about how to do this for a while because I was aware of the dead node, but did not think that had anything to do with the upgrade. Maybe I should type a quick howto for ejabberd.jabber.ru?
In any case I am happy the upgrade was a success! 🙂