This article explains an important method used to check your Munin config file. This is not checking the ‘munin-nodes’ but just the ‘munin.conf’ file. The key is to switch to the ‘munin’ user and then issue the ‘munin-update’ command. As follows:
On the Munin server, login as root. Then switch to the ‘munin’ user.
su - munin --shell=/bin/bash
And then issue the command:
/usr/share/munin/munin-update --debug
You will get the line number of the error troubling you, if all goes well.