The problem

I recently got me a bunch of mails from cron, informing me about a failure

File is not a perl storable at /usr/lib/perl/5.18/Storable.pm line 398, at /usr/share/perl5/Munin/Master/Utils.pm line 279.

Most of the graphs (but not all graphs) for a host was not displaying correctly. Instead of the graph I saw the actual data.

Not really finding any relevant answers to my querys on Google, I found this page. Not exactly the same error, but I did find some valuable information about how to further investigate the problem.

The solution

Run munin-cron as user munin to see if displays anymore information about the problem: