It sounds like the upgrade didn't fully complete. Try SSHing in as root and running :
Created: Sat Jan 25, 2014 12:30 AM UTC by Dewono Siswardiyanto
Last Updated: Sat Jan 25, 2014 12:30 AM UTC
After upgrading to 1.670, I cannot access my Apache Webserver module. Also some module on the Webmin, such as updating Software Packages Update, Filesystem Backup, etc.
Is there a workaround or how to reinstall web min without changing my settings? Thanks.