That's a really huge upgrade for you. Do you want to keep any student data? If not, I would really consider installing a fresh new copy of Moodle instead of trying to do an upgrade.
You can export your student details to csv on the 1.9 site and then import their accounts into the fresh new site.
The Moodle coure backup format changed completely a few versions back. I would check the Moodle release notes (https://docs.moodle.org/dev/Releases) and see which version that was. Then I'd upgrade the 1.9 site to that version. Then I'd backup all the courses to the .mbz backup format. Then I'd use those .mbz backup files to restore the courses into the new Moodle server that's running the latest version of Moodle.
Then I'd put a note in my diary to upgrade Moodle more regularly.
This is of course only necessary if you do want to migrate any courses to the latest version of Moodle. If not then just drop that 1.9 installation and start fresh with a new clean version. It will prevent a lot of new grey hairs appearing on your head!
You can export your student details to csv on the 1.9 site and then import their accounts into the fresh new site.
The Moodle coure backup format changed completely a few versions back. I would check the Moodle release notes (https://docs.moodle.org/dev/Releases) and see which version that was. Then I'd upgrade the 1.9 site to that version. Then I'd backup all the courses to the .mbz backup format. Then I'd use those .mbz backup files to restore the courses into the new Moodle server that's running the latest version of Moodle.
Then I'd put a note in my diary to upgrade Moodle more regularly.
This is of course only necessary if you do want to migrate any courses to the latest version of Moodle. If not then just drop that 1.9 installation and start fresh with a new clean version. It will prevent a lot of new grey hairs appearing on your head!