Ubuntu 22.04, osTicket 1.18 - I was able to resolve these errors and get a duplicate system running.
installed on a test machine, setup on 2nd system as a possible production box.
disclaimer: DON'T DO ANY of this until you do your own research and feel comfortable blowing your install out of the water and starting from scratch.
The HTTP 500 issue was resolved by uninstalling Apache2 and PHP, rebooting, reinstalling.
The MySQLi missing error was resolved by running: apt remove –purge phpMyAdmin
apt install phpMyAdmin.
The process I used to move the database from the test server to the prod. server was fairly straightforward, but it did take me some time to find the correct commands to get the database moved.
To move the SQL database from the existing test machine to the prod. machine: On the existing (source) machine, ran the following command: mysqldump -uroot -p osticket_db > osticket_db.sql
then copied this file to the new machine using this command: scp osticket_db.sql username@ser.ver.ip:osticket_db.sql
On the new machine, run: mysql -uroot -p osticket_db < osticket_db.sql
when I typed in the IP on the new server, I was prompted to run the osTicket upgrade and it upgraded as well as moved all of the existing data, tickets, etc. worked nicely. check your permissions and a bit of trouble resolved by using the chmod command on this one. There are only a few Ubuntu install procedures I found online, and they all seemed to be fairly accurate. The MySQLi extension for PHP Missing! error gave me the most trouble, and it's not really clear when you're troubleshooting what the commanding version of PHP is. osTicket will indicate one version is active, when you type php -v from a command line, another version may pop up. one command I found helpful that shows you what php versions you have installed and available to choose from is:
update-alternatives --config php
this will show you installed PHP versions and give you the option to change versions, if there are more than one.
Now, I know all of this information out there, but these were the issues I had and resolved with various iterations of these commands. I hope this is of some use to the noobs getting into new installs like me.
