Ubuntu 18.04.1 (upgraded from 16.04.4), module Webminstats 2.18, when clicking on the "Check config", the log shows many of these same lines: (also after clearing the logs they come back, one line per click)
web_log : /var/webmin/modules/sysstats/webminstats.debug
[Tue Sep 18 18:26:25 2018] miniserv.pl: Use of uninitialized value $miniserv::config{"nolog"} in split at /usr/share/webmin/miniserv.pl line 3138.
I don't even see anything like that in /usr/share/webmin/miniserv.pl
Also the ipv4 firewall module is not working either (but that seems to be a known thing.)
Or did the upgrade maybe remove some necessary perl module? (I faintly remember something like that.)
These are just warnings and they are harmless. We will fix that.
Thanks.
Also, the webminstats module isn't a core part of webmin - so you'd need to contact it's author about this.
Actually, this is coming from the webmin core - I will fix it in the next release.