Welcome! Glad to hear it .. now some food for thought and suggestions ... my method of moodle madness!
Version of Moodle
https://moodledev.io/general/releases
4.2 is now 4.2.11 and no longer getting any fixes to code or security updates.
4.5 is a long term support version and is 4.5.6+ now - support until October 2027 - 2 years from now.
5.0 is a .0 and is now 5.0.2+ not a long term support version
In that series, 5.3 is the next LTS and it hasn't been released yet. What is in 5.0 that you just have to have?
I take it you are not using git for core versioning of moodle code, but, rather using the old method of upgrading which has too many moving parts, IMHO!
What's the end game here? Getting same courses ready to take on new students?
If that's the case, could make a looping bash shell script to backup all 300+ courses that have users in them to a destination directory (outside of moodledata/filedir/)
Those are your record retention copies.
Then install moosh and use the moosh command to reuse courses ... remove all role ID 5 (students) from the existing courses leaving only the teachers and the content.
https://moosh-online.com/commands/#course-reset
Question about resetting ... are you the teacher in all of those 300+ courses?
Are you sure the teachers in those courses are done with them? Why not let teachers reset (called reuse in the menus of Moodle)?
'SoS', Ken