I updated one of my CentOS 6 servers the other day to Plesk Obsidian. Now I have a customer that's trying to use webmail that reports an error "IMAP error reported by server" when he uses Horde on his inbox. Any ideas on how to debug and fix?
I've just upgraded to Obsidian and had exactly the same problem. I can confirm that the suggested patch in the linked discussion fixed the problem for me.