Ubuntu 16.10’s intended release-upgrade path was to 17.04 or the next release, with the upgrade path disappearing when 17.04 reached EOL.
LTS releases have two upgrade paths:
- to the next release like your 16.10 non-LTS had (to 17.04), or
- to the next LTS release (an unsupported path for non-LTS unless from prior release)
If it was me, I’d backup all data on your system, and either
- clean install & restore the data you need
- unclean install a supported release of Lubuntu over your existing install…
The clean install I’d expect to have best results; and do note I’d only restore the data you need given how old your system is, rather than everything - but that’s me.
The unclean install I’d use is documented here and listed as “Install using existing partition” being something we test in our Quality Assurance testing, however do NOTE as 16.10 is so old & past EOL, I’d perform homework where data matters to you before I actually did it prior to doing it, given you’re talking about doing a unclean install with a very different system; esp. if your data matters to you.
Also FYI: Returning to 16.04 may not help you either, as it’s path to 18.04 really ended when EOSS was reached and that upgrade path closed anyway (though it may still work; but problems would now be expected given it’s no longer a supported upgrade due to EOSS).
FYI: I really like the unclean install method I mention, and often use it as faster than normal release-upgrades, however it’s results will vary depending on what 3rd party packages you have installed, as QA of it only include Ubuntu repository packages.