the installer expects to file lib/imap.inc to be available (it is called iilConnection in the extension list). The lib/imap.inc file is however in ../programs/lib/ and not in lib/
Easy to fix but the installer is useless without the fix.
looks like I have a problem with ini_set after upgrading. I do however not have that problem elsewhere on the server (or before I used the installer to upgrade the webmail installer config). What could have this impact on the webmail installation?