Re: On the plus side
Do they make it easy now? in the past it was not a supported path to do a major version upgrade. I upgraded my company's systems from 10.04 to 12.04 years ago and the process at the time was entirely unsupported, and it took many hours of trial and error to get a robust way to do the upgrade.
Debian by contrast (debian user since 1998) has always(as far as I know) supported major version upgrades. I believed since Ubuntu was based on Debian it should of been possible to do a major version change on Ubuntu even if it wasn't supported (thankfully we have VM level snapshots where I was able to test, break, revert snapshot, test break, revert snapshot until I figured it out)
And for those more techie, to give an example as what I had to do to do the upgrade, here is a snip from the script:
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export DEBIAN_FRONTEND=noninteractive
debconf-set-selections /mnt/scratch/tmp/ubuntu-upgrade/precise.preseed
apt-get -y -o Dpkg::Options::="--force-confdef" -o Dpkg::Options::="--force-confold" upgrade
debconf-set-selections /mnt/scratch/tmp/ubuntu-upgrade/precise.preseed
apt-get -y -o Dpkg::Options::="--force-confdef" -o Dpkg::Options::="--force-confold" install dpkg util-linux
apt-get -y -f install -o APT::Immediate-Configure=false python2.7-minimal passwd
debconf-set-selections /mnt/scratch/tmp/ubuntu-upgrade/precise.preseed
apt-get -y -o Dpkg::Options::="--force-confdef" -o Dpkg::Options::="--force-confold" dist-upgrade
debconf-set-selections /mnt/scratch/tmp/ubuntu-upgrade/precise.preseed
apt-get -y -o Dpkg::Options::="--force-confdef" -o Dpkg::Options::="--force-confold" install nsca-client
apt-get -y -o Dpkg::Options::="--force-confdef" -o Dpkg::Options::="--force-confold" install nfs-common
apt-get -y install vmware-open-vm-tools-kmod-3.2.0-41-generic
dpkg --purge linux-headers-2.6.32-37 linux-headers-2.6.32-37-server linux-image-2.6.32-37-server vmware-open-vm-tools-kmod-2.6.32-37-server
apt-get -y autoremove
dpkg --get-selections | grep deinstall | awk '{print $1}' |xargs dpkg --purge
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It wasn't a simple apt-get dist-upgrade by any stretch ! I had to upgrade those named packages in that order else the upgrade would not complete. There was more to the script but that was the core dpkg stuff I used to upgrade from 10.04 LTS -> 12.04 LTS. I recall an earlier version of Ubuntu was it 7 or 8 maybe I had installed on my sister's laptop, I went through their GUI dist upgrade on that system and it mostly worked but still required some command line magic to get it to complete(I think it got halfway done and when I rebooted X was broken turns out there was a hundred or so packages that did not upgrade the first time round). Had a similar experience upgrading Mint recently on one of my laptops (I believe I read mint has a no upgrade policy too, though in the Mint experience I just clicked the upgrade button it wanted me to click on to upgrade, so I think that should of worked).
I remember back in the early days of Fedora where they had 6 month cycles(maybe still do haven't had to use Fedora since 2007) they too had a no upgrade policy, and I think back then it was far more dicey to upgrade Fedora rather than reinstall, though I think I read in recent years that it is possible to do major version changes in fedora without reinstalling.