I get this error when deleting a message.
Connection to storage server failed.
I just upgraded from 0.5.3 - 0.8.2-release
I ran all the mysql commands from mysql.update.sql
I see nothing in the logs and have no clue how to troubleshoot what is wrong.
It obviously is something wrong in the database, because if I do a fresh install of database everything works fine.
I think my problem pertains to the same issue as in this thread:
http://www.roundcubeforum.net/index.php/topic,10389.0.html