Comment 44 for bug 1279762

Well, I seemed to have worked out my solution to getting around this issue. It was a couple more hours than I expected, and I had to clean up a broken package or two, but everything seems to be working now. Could some of the ideas below be used to fix this bug?

#1 Do steps 2, 3, and 4 of this article. (Step 1 isn't necessary, because I am already at 13.10; I decided that Step 5 wasn't necessary either).

http://alankeister.wordpress.com/2014/01/03/how-to-upgrade-ubuntu-to-mint-mate-16-petra-desktop/

#2 Go to this stack overflow article, and follow this guide.

http://superuser.com/questions/755574/terminal-command-to-upgrade-from-linux-mint-16-to-linux-mint-17

Especially:

"$ sudo sed -i 's/saucy/trusty/' /etc/apt/sources.list

$ sudo sed -i 's/petra/qiana/' /etc/apt/sources.list

$ sudo sed -i 's/saucy/trusty/' /etc/apt/sources.list.d/official-package-repositories.list

$ sudo sed -i 's/petra/qiana/' /etc/apt/sources.list.d/official-package-repositories.list

Use sed to replace references to saucy with trusty, and petra with qiana in the sources

(If you don't have /etc/apt/sources.list.d/official-package-repositories.list, as I didn't, then you can do the sed stuff just in /etc/apt/sources.list)

$ sudo apt-get update && sudo apt-get dist-upgrade

$ sudo apt-get upgrade

Update the repositories with the new settings and run a dist-upgrade to upgrade to the new version cleanly, then run upgrade to make sure all the packages are updated."

This took me three hours to run, but the result appears to be a nice version of Ubuntu 14.04 (with a few bits of Linux Mint stuff added in). While installing, there were lots of messages of the form:

"GdkPixbuf-WARNING **: Cannot open pixbuf loader module file '/usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0/2.10.0/loaders.cache': No such file or directory

This likely means that your installation is broken.
Try running the command
  gdk-pixbuf-query-loaders > /usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0/2.10.0/loaders.cache"

But these messages seem to be more cosmetic (and correspond to an existing bug):

https://bugs.launchpad.net/ubuntu/+source/gdk-pixbuf/+bug/1282294

#3 There will be a few minor packages that may be broken at the end of #2; for example, mate-polkit was broken on mine. So without rebooting, I uninstalled and reinstalled them after #2 was completed.

The irony is that Cinnamon ended up broken at the end of the installation process. On the other hand, I was able to get 14.04 on my machine without installing Cinnamon. Once I found that I couldn't log into Cinnamon, I uninstalled it and reinstalled it to fix it straight away.

So for me, it was 13.10 -> lengthy 3 hours installation -> 2 minute uninstall and reinstall of Cinnamon. For some reason, I felt this gave me a better change of preserving my settings than 13.10 -> uninstall Cinnamon -> lengthy 3 hour installation -> reinstall Cinnamon (and possibly losing settings).

Other drawback of this process: now I don't have Unity. But then I never used it.