How to upgrade kubuntu 16.04 -> KDE neon

kubuntu-to-neon.md

This worked for me and might not work for your.

Try it at your own risk!

Add the neon repositories and install the neon desktop

$ wget -qO - 'http://archive.neon.kde.org/public.key' | sudo apt-key add -
$ sudo apt-add-repository http://archive.neon.kde.org/user
$ sudo apt-get update
$ sudo apt-get install neon-desktop

Upgrade everything. Repeat if necessary, until everything is really up to date and you have no held-back packages.

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

sudo apt-get install neon-desktop

Is it necessary? What does it bring extra?

Thanks buddy, though this line was very important "Upgrade everything. Repeat if necessary, until everything is really up to date and you have no held-back packages", had a tough time upgrading it, thanks by the way!

If anyone stumbles upon this: DO NOT TRY! There is a very high probability it will screw your plasma or sddm just like it did to me.

If it's too late and you already did screw it you could try:

sudo apt-get install --reinstall neon-desktop plasma-desktop plasma-desktop-data sddm xorg xserver-xorg-core xserver-xorg-video-akk && sudo dpkg-reconfigure sddm
Thanks to: http://askubuntu.com/questions/761358/kubuntu-doesnt-work-after-upgrade-to-16-04/761379#761379 for the idea. But still I had to go through more hoops to solve all my problems.

PS: If you want the neon LTS version (which has plasma 5.8.* not 5.9.* as of the time of writing this) then:
sudo apt-add-repository http://archive.neon.kde.org/user/lts
instead of
sudo apt-add-repository http://archive.neon.kde.org/user

This worked great for me. Thank you,

Also tried this from ubuntu gnome 16.04, worked perfectly.

How I fixed (Ubuntu 16.04 Xenial) non-upgradeable state after doing the above (sudo apt-get update --fix-missing dpkg –configure -a apt-get install -f didn't seem to help but may):

(after EACH step below, do sudo apt update && sudo apt upgrade and sudo apt dist-upgrade again)

• When packages were held back I had to to apt install packagename
  (actually for MANY packages, so pasted them [list of packages held back may be found via apt upgrade or apt dist-upgrade] to a list file then installed mass packages from a file)
• When packages were in conflict, I removed them with apt remove packagename (as shown in upgrade or dist-upgrade conflict error such as: "packagename breaks something but packagename-y is set to be installed").
• After everything, sudo apt install neon-desktop again since some of the removed conflicting files were dependencies
• Plasma (Wayland) didn't work (froze display), so did Ctrl+Alt+Del then after reboot I chose regular Plasma from the session menu before clicking login (Wayland may only fail with certain video card and driver combinations--I have "Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)").

Now my desktop works better than ever (faster and more stable) even though the system was changed from Ubuntu to Kubuntu (where I did a similar) to Neon!

some apt -f install and apt autoremove between upgrades also helps to solve problems

Thanks, worked for about 2 months ago. No problems since!

Updating programs to latest neon version works (after adding the ppa, the system can now find the latest versions of the kde programs)

but installing neon-desktop requires additional packages that are not installable on my system apparently

I imported to more gpg keys:

• Key 1 - signing key for Neon releases: https://keyserver.ubuntu.com/pks/lookup?op=get&search=0xDEACEA00075E1D76
• Key 2 - signing key for Neon packages: https://keyserver.ubuntu.com/pks/lookup?op=get&search=0xE6D4736255751E5D

The 2nd one (0xE6D4736255751E5D) was important to be able to add the neon repository to my apt lists and "apt update" successfully!

Oh. And I had troubles with KDE games, so I remove as much as I could, by doing:
sudo apt remove kmahjongg kmines kpat ksudoku libkf5kdegamesprivate1 libkf5kdegames7 libkf5kmahjongglib-data libkf5kmahjongglib5 kdegames-mahjongg-data-kf5 kdegames-card-data-kf5 libgamemode0 libgamemodeauto0 libkf5kdegames-data

and to make sure all dependencies are finally correct:
sudo apt-get dist-upgrade

Thanks for this. I had some minor problems upgrading from Kubuntu 20.04 LTS, but figured it out; Here's what I did in case anyone else encounters the same issue.

Note that once apt has been updated, sudo apt upgrade will no longer work, and you will have to use sudo pkcon update, as is the KDE neon way.

Every so often while doing sudo apt dist-upgrade, dpkg would error out, saying a package (from neon) tried to overwrite a file provided by another package (same, already install package from ubuntu), and it won't let you remove the package with sudo apt remove package. To get around this, for each broken package (I had ~20 in total):

1. sudo dpkg -i --force-overwrite /var/cache/apt/archives/package.deb (replace path with the one provided by the dpkg error message)
2. sudo apt --fix-broken install -y
3. sudo apt update && sudo apt dist-upgrade -y

Repeat these steps for every package that breaks in this way, and eventually, the dist-upgrade will go through with no errors. Do another sudo apt install neon-desktop and sudo apt autoremove to make sure everything is up to date. After a reboot, everything booted up without error.