We have several issues that have been occurring for quite some time which makes it very difficult to determine what may have changed to create these problems. I'm not even sure if they're related.
1. In the Monitoring Engine Status screen, the Monitoring Engine Process is showing no data.
2. On the same screen, the Monitoring Engine Event queue is getting and Error: No output from backend!
3. On the CCM screen, the Apply Configuration option does not work. We must login to the server and run the reconfigure_nagios.sh to apply a new config.
4. On the Service Status Detail screen, when attempting to Force and immediate check, this is returned - Your request was not processed in a timely manner. It may still execute, as the server may be temporarily busy.
I have repaired the databases, restarted Nagios, and rebooted the server numerous times. Looking for recommendations. We are running Nagios XI Version : 5.4.12 on RHEL 7.