After upgrading to Nagios XI 5.3.0 you no longer receive any notifications.
The initial release of Nagios XI 5.3.0 had an incorrect file that is the source of the problem.
Solution
As of 9am UTC October 4th an updated 5.3.0 release with the correct file was published.
To resolve the issue, download the updated 5.3.0 release and perform a manual upgrade. Notifications will work once re-applying the upgrade.
Manual upgrade instructions:
Nagios XI - How to Manually Update Nagios XI
Alternatively you can replace just the individual file that was the source of the problem by following these steps:
cd /tmp
rm -rf xi-*.tar.gz nagiosxi
wget https://assets.nagios.com/downloads/nagiosxi/5/xi-5.3.0.tar.gz
tar xf xi-5.3.0.tar.gz
cp nagiosxi/nagiosxi/basedir/html/includes/utils-events.inc.php /usr/local/nagiosxi/html/includes/
Final Thoughts
For any support related questions please visit the Nagios Support Forums at:
http://support.nagios.com/forum/
Article ID: 545
Created On: Tue, Oct 4, 2016 at 7:29 PM
Last Updated On: Tue, Oct 4, 2016 at 9:34 PM
Authored by: tlea
Online URL: https://support.nagios.com/kb/article/nagios-xi-notifications-not-sending-in-xi-5-3-0-545.html