Need procedure to migrate from 5.5 on Centos 6.9-based VM

[rpike]

We have been running NagiosXI 5.5 which we cannot upgrade any further on the Centos 6.9-based Nagios VM.
We need to migrate to a new environment which we want to start with the latest Centos 7.9-based nagios VM.

My current understanding is that we will need to:
1. downgrade the new VM from 5.8.5 to the 5.5 version we are currently running (and from which the backups are taken)
2. restore the backup from the current 5.5 system
3. once running successfully we can then run the Nagios upgrade to birng it up to the current version

What is the best way to downgrade the new VM from 5.8.5 to 5.5?
I tried to figure out a way on my own, but the 5.5 install ended with:

===============
SETUP COMPLETED
===============
### NAGIOS XI TRAP INTERFACE INSTALL SCRIPT ###
NXTI already installed
Nagios XI base files installed OK
Crontabs installed OK
usage: see firewall-cmd man page
No option specified.
npcd.service is not a native service, redirecting to /sbin/chkconfig.
Executing /sbin/chkconfig npcd on
Created symlink from /etc/systemd/system/multi-user.target.wants/ndo2db.service to /usr/lib/systemd/system/ndo2db.service.
Daemons configured to start OK
Applying patches to Apache configs for Apache 2.4.x syntax...
Sleeping...
NOTE: If prompted, enter the MySQL root password
ERROR: Cannot connect to CCM's nagiosql database - exiting. Were MySQL and CCM installed?

[gsmith]

Hi

Use this link:
https://assets.nagios.com/downloads/nag ... ion-64.ova
and substitute for the version of 5.5 you are running.

If you were running xi-5.5.5 you would use:
https://assets.nagios.com/downloads/nag ... 5.5-64.ova

That will give you Nagios XI 5.5.5 on a Centos 7 VM. Then you can restore
your backup and verify it works.
Next you can upgrade Nagios XI to the current version.

Thanks