Acknowledge Fails Missing New Servers after 5.5.1 Upgrade

[fsbeaunix]

Just updated two XI instances to 5.5.1 and have the same problem on both servers.

Issue: Acknowledge alerts does not work & new hosts added in Configuration Manager do not show up in Host Status

I have multiple instances of nagios parent processes:

root 10329 16531 0 15:24 pts/0 00:00:00 grep nagios.cfg
nagios 19811 1 0 Feb23 ? 00:26:26 /usr/local/nagios/bin/nagios -d /usr/local/nagios/etc/nagios.cfg
nagios 19826 19811 0 Feb23 ? 00:10:53 /usr/local/nagios/bin/nagios -d /usr/local/nagios/etc/nagios.cfg

killall -9 nagios
nagios restart

This will temporarily fix the issue. After this, new servers show up. But a double instance of nagios loads again and any new servers will not show up again until I run killall -9 nagios & nagios restart.

I've checked file permissions and ownership - everything looks good. Config File verified the config files seem OK.

I have two Nagios instances. One is a production server that broke first after the update. Then I remember I have a simple NagiosXI instance setup in test with bare minimum configs. It was working fine. After I updated test, it now has the exact same problem as production. I know, I probably should have updated Production first. But this seems to point to something in the update is not working as expected.

Red Hat 6.9 - patches up to date

Interesting: Handling: 72=ndomod: Error writing to data sink! Some output may get lost...

[scottwilkerson]

root 10329 16531 0 15:24 pts/0 00:00:00 grep nagios.cfg
nagios 19811 1 0 Feb23 ? 00:26:26 /usr/local/nagios/bin/nagios -d /usr/local/nagios/etc/nagios.cfg
nagios 19826 19811 0 Feb23 ? 00:10:53 /usr/local/nagios/bin/nagios -d /usr/local/nagios/etc/nagios.cfg

this is not a double parent process, this is one parent and 1 child, but running since Feb23 ?

Can that be right? Is the date connect on these machines?