This question already has an answer here:
I've tried a few ways online (though they seem to be different ways of doing the same thing).
And I always get this message:
An upgrade from 'zesty' to 'bionic' is not supported with this tool.
I saw in another post on this forum, that you have to upgrade in order? Meaning, I apparently need to upgrade my 17.04 installation to 17.10, and then I can upgrade to 18.04. Which is fine, I have enough free time to do that, however... how? How do I upgrade from 17.04 to 17.10 now that 18.04 is out?
And I would highly appreciate a solution that doesn't just involve reinstalling the OS. Because while I do already have a flash drive with 18.04 on it via Rufus, I do not have the knowledge of Linux required to get all my save data for my applications (namely games), and back it up, because I don't understand where Linux and it's applications store their data.
Finally, I don't know if this matters at all, but just so it's on the record: this is a dual boot setup. PC had Windows, before I slipped Ubuntu in the side :p .
-- I would like to reiderate, that I want to upgrade from 17.04 to 17.10, and then from 17.10 to 18.04. I would also like to point out that the official upgrade tutorial does not seem to bother mentioning that 17.04 users will have a hard time (or possibly even can't!) upgrade, which is odd to me only because it does mention that for users on 15.10, to read an upgrade notes page on the Ubuntu site. So they are aware of people trying to do large leaps in versions.
I get an error when executing the second command in the answer:
E: Problem executing scripts APT::Update::Post-Invoke-Success 'if /usr/bin/test -w /var/cache/app-info -a -e /usr/bin/appstreamcli; then appstreamcli refresh-cache > /dev/null; fi' E: Sub-process returned an error code
If I put a 17.10 iso on a flash drive, and booted from that, would I be given the option to upgrade to that version? The reason I ask, instead of just trying it myself, is because I'd rather not waste the time downloading such a large file, for it not to work.