==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.3.2 MARIADB edition.
- Deployed with iRedMail Easy or the downloadable installer? NO
- Linux/BSD distribution name and version: Red Hat Enterprise Linux Server release 7.8 (Maipo)
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):  MySQL (MariaDB)
- Web server (Apache or Nginx): Nginx
- Manage mail accounts with iRedAdmin-Pro? Yes
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

After ran the upgrade_iredadmin.sh script to update my server goes completely down, I figure out the problem, it on line 62 of the update script, by getting a wrong RHEL version in:

export DISTRO_VERSION=$(awk -F'"' '/^VERSION_ID=/ {print $2}' /etc/os-release) -> this line resolve to 7.8 instead of 7 as expected by the script

----- content of /etc/os-release ------
root@plaltcorreo01~$more /etc/os-release
NAME="Red Hat Enterprise Linux Server"
VERSION="7.8 (Maipo)"
ID="rhel"
ID_LIKE="fedora"
VARIANT="Server"
VARIANT_ID="server"
VERSION_ID="7.8"
PRETTY_NAME="Red Hat Enterprise Linux"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:redhat:enterprise_linux:7.8:GA:server"
HOME_URL="https://www.redhat.com/"
BUG_REPORT_URL="https://bugzilla.redhat.com/"

REDHAT_BUGZILLA_PRODUCT="Red Hat Enterprise Linux 7"
REDHAT_BUGZILLA_PRODUCT_VERSION=7.8
REDHAT_SUPPORT_PRODUCT="Red Hat Enterprise Linux"
REDHAT_SUPPORT_PRODUCT_VERSION="7.8"

---------------------------------

----- Logs from the update script -----
root@plaltcorreo01~/iRedAdmin-Pro-SQL-4.7/tools$bash upgrade_iredadmin.sh
* Detected Linux/BSD distribution: RHEL
* HTTP server root: /var/www
* Found iRedAdmin directory: /var/www/iredadmin, symbol link of iRedAdmin-Pro-SQL-4.6
* Found iRedAdmin config file: /var/www/iredadmin/settings.py
* Copying new version to /var/www/iRedAdmin-Pro-SQL-4.7
* Copy /var/www/iredadmin/settings.py.
* Remove existing systemd service files.
* Copy systemd service file: /lib/systemd/system/iredadmin.service.
cp: cannot stat '/var/www/iRedAdmin-Pro-SQL-4.7/rc_scripts/systemd/rhel7.8.service': No such file or directory
Can't open /lib/systemd/system/iredadmin.service: No such file or directory.
chmod: cannot access '/lib/systemd/system/iredadmin.service': No such file or directory
* Removing old symbol link /var/www/iredadmin
* Creating symbol link /var/www/iredadmin to /var/www/iRedAdmin-Pro-SQL-4.7
* Enable mlmmj integration.
* Restarting service: mlmmjadmin.
* Check and install required packages.
* Check SQL tables, and add missed ones - if there's any
* Replace py2 by py3 in cron jobs.
* Clean up.
* Delete all existing sessions to force all admins to re-login.
* iRedAdmin has been successfully upgraded.
* Restarting iredadmin service.
Redirecting to /bin/systemctl restart iredadmin.service
Failed to restart iredadmin.service: Unit not found.
Failed, please restart Apache web server or 'iredadmin' (if you're running Nginx as web server) manually.
* Enable service: iredadmin
Failed to execute operation: No such file or directory
Failed to restart iredadmin.service: Unit not found.
Failed, please restart service manually and check its log file.
* Upgrading completed.
<<< NOTE >>> If iRedAdmin doesn't work as expected, please post your issue in
<<< NOTE >>> our online support forum: http://www.iredmail.org/forum/
---------------------------------------------

To solve the problem I manually ran this commands:

cp -f /root/iRedAdmin-Pro-SQL-4.7/rc_scripts/systemd/rhel7.service /lib/systemd/system/iredadmin.service
perl -pi -e 's#/opt/www#/var/www#g' /lib/systemd/system/iredadmin.service
systemctl daemon-reload
systemctl enable iredadmin.service
systemctl start iredadmin.service

systemctl status iredadmin.service
  iredadmin.service - iRedAdmin daemon service
   Loaded: loaded (/usr/lib/systemd/system/iredadmin.service; enabled; vendor preset: disabled)
   Active: active (running) since Fri 2021-02-12 02:21:42 CST; 11s ago
  Process: 5882 ExecStartPre=/usr/bin/chmod 0755 /var/run/iredadmin (code=exited, status=0/SUCCESS)
  Process: 5879 ExecStartPre=/usr/bin/chown iredadmin:iredadmin /var/run/iredadmin (code=exited, status=0/SUCCESS)
  Process: 5877 ExecStartPre=/usr/bin/mkdir /var/run/iredadmin (code=exited, status=0/SUCCESS)
Main PID: 5885 (uwsgi)
   CGroup: /system.slice/iredadmin.service
           ├─5885 /usr/sbin/uwsgi --ini /var/www/iredadmin/rc_scripts/uwsgi/rhel7.ini --pidfile /var/run/iredadmin/iredadmin.pid
           ├─5888 /usr/sbin/uwsgi --ini /var/www/iredadmin/rc_scripts/uwsgi/rhel7.ini --pidfile /var/run/iredadmin/iredadmin.pid
           ├─5889 /usr/sbin/uwsgi --ini /var/www/iredadmin/rc_scripts/uwsgi/rhel7.ini --pidfile /var/run/iredadmin/iredadmin.pid
           ├─5890 /usr/sbin/uwsgi --ini /var/www/iredadmin/rc_scripts/uwsgi/rhel7.ini --pidfile /var/run/iredadmin/iredadmin.pid
           ├─5891 /usr/sbin/uwsgi --ini /var/www/iredadmin/rc_scripts/uwsgi/rhel7.ini --pidfile /var/run/iredadmin/iredadmin.pid
           └─5892 /usr/sbin/uwsgi --ini /var/www/iredadmin/rc_scripts/uwsgi/rhel7.ini --pidfile /var/run/iredadmin/iredadmin.pid

Feb 12 02:21:42 plaltcorreo01.*** iredadmin[5885]: mapped 437520 bytes (427 KB) for 5 cores
Feb 12 02:21:42 plaltcorreo01.*** iredadmin[5885]: *** Operational MODE: preforking ***
Feb 12 02:21:42 plaltcorreo01.*** iredadmin[5885]: WSGI app 0 (mountpoint='') ready in 0 seconds on interpreter 0x1657a40 pid: 5885 (default app)
Feb 12 02:21:42 plaltcorreo01.*** iredadmin[5885]: *** uWSGI is running in multiple interpreter mode ***
Feb 12 02:21:42 plaltcorreo01.*** iredadmin[5885]: spawned uWSGI master process (pid: 5885)
Feb 12 02:21:42 plaltcorreo01.*** iredadmin[5885]: spawned uWSGI worker 1 (pid: 5888, cores: 1)
Feb 12 02:21:42 plaltcorreo01.*** iredadmin[5885]: spawned uWSGI worker 2 (pid: 5889, cores: 1)
Feb 12 02:21:42 plaltcorreo01.*** iredadmin[5885]: spawned uWSGI worker 3 (pid: 5890, cores: 1)
Feb 12 02:21:42 plaltcorreo01.*** iredadmin[5885]: spawned uWSGI worker 4 (pid: 5891, cores: 1)
Feb 12 02:21:42 plaltcorreo01.*** iredadmin[5885]: spawned uWSGI worker 5 (pid: 5892, cores: 1)

Hopefully this information help to deal with this problem for future updates

Regards