If for some reason, your Nagios server stops sending out host alerts it’s more than likely that recent update broke it. If that is the case, you will need to re-run the update, which should fix the issue. In the event that this does not fix the problem, check your email settings in nagios.
This same method can be used to manually update Nagios instead of using its automated update feature
Type these commands into your terminal session:
Next, download the following update file from the Nagios website.
Once that has been downloaded to /tmp you will need to unzip the tar.gz file.
tar xzf xi-latest.tar.gz
Now that it is unzipped, go ahead and move to the new directory
Go ahead and list the content is /tmp/nagiosxi
ll or ls -l
You should see an executable file name “update”. Run that script.
It will take a bit, but you shouldn’t see any issues and if it reports a bug fix, note which one. After that, emails should start flowing through again. On top of that, the system will be up to date.