I’d guess as there is database corruption errors in your logs that is why the upgrade is failing. It’s most likely the plex server is trying to apply database changes and then failing.
I’d suggest you try the repair procedure Repair a Corrupted Database | Plex Support and then once the errors are resolved then try the upgrade.
Also, while reverting to the previous version may appear to work it may not for long considering the corruption in your db.
On the OS question… F29 is ancient and would not be supported by fedora anymore so your open to security holes etc due to not getting patches.
