After the Munin YUM update, I got this error in my browser when I visited my Munin web interface:
Software error:
Can't use an undefined value as an ARRAY reference at /usr/share/perl5/vendor_perl/Munin/Master/HTMLOld.pm line 773.
For help, please send mail to this site's webmaster, giving this error message and the time and date of the error.
I investigated the cause of this error and found out that the /var/lib/munin/htmlconf.storable is not present. The Munin scipts should auto generate this file when the system cron runs. I debugged what prevents Munin cron script from generating this file and discovered that the Munin update replaced the /etc/munin/munin.conf configuration file. The new configuration file commented all the default enabled configurations from the old version, the only uncommented line is:
includedir /etc/munin/conf.d
The lines that should be uncommented that will not prevent Munin cron from generating the /var/lib/munin/htmlconf.storable file are the following:
[localhost]
address 127.0.0.1
use_node_name yes
After enabling the lines above in the Munin configuration wait for the Munin cron runs and the error should now be fixed. If you want to test without waiting for the cron to run, execute the following commands:
su - munin --shell=/bin/bash
/usr/bin/munin-cron
... then browse the Munin web interface and it should render without error.