Nagios Support Forum

I got this message too.
I looked at:
ccm-hosts-manage parent = empty
associated templates-parent = empty

This is a somewhat older topic and there were a few troubleshooting steps performed. I am going to split this into a new topic so we don't make any assumptions. Link to the old for reference: http://support.nagios.com/forum/viewtop ... f=6&t=9605

For starters, can you go to Configure -> Core Config Manager, then on the left under Tools click Write Config Files. Then click Delete, then Write, and finally Verify and post a screenshot.