Clamav update is broken since upgrade to webmin 6.0 from 5.99. The following error occurs:
Cron root@webhost /usr/share/clamav/freshclam-sleep
ERROR: getpatch: Can’t download daily-23699.cdiff from database.clamav.net
That’s unrelated to the Virtualmin module update.
Try running freshclam from the command line and see if any useful errors show up.
This work for me 