Are you maybe sitting and wondering if you can safely upgrade from Ubuntu 16 → Ubuntu 18?
I was having exactly the same thought and why not give it a go! 
For starters not all server setup are equal but my base was a:
-
Former UB 16 minimal install on Hetzner raid 0
-
Newest Quickbox Pro version
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Running rtorrent/rutorrent, iRSSi-AutoDL, Jackett, Netdata, Ombi, Plex, Syncthing, Tautulli and Web Console
Before you start give some thought into this - could I simply uninstall the app before upgrade?
It will save you some time for the upgrade process!
I would remove Netdata, Ombi, Syncthing and Tautulli if I had to do it again!
Before upgrading to Ubuntu 18.04, you should first update the current 16.04. It’s recommended to update/upgrade all installed packages before upgrading. To update Ubuntu, connect to the server and run the commands below:
sudo su -
then
apt update && sudo apt dist-upgrade && sudo apt autoremove
After updating Ubuntu 16.04 server, run the commands below to install update-manager-core if it is not already installed.
apt-get install update-manager-core
Then open the update-manager configuration file and make sure the Prompt line is set to lts
nano /etc/update-manager/release-upgrades
Confirm that the Prompt is equal lts
# Default behavior for the release upgrader.
[DEFAULT]
# Default prompting behavior, valid options:
#
# never - Never check for a new release.
# normal - Check to see if a new release is available. If more than one new
# release is found, the release upgrader will attempt to upgrade to
# the release that immediately succeeds the currently-running
# release.
# lts - Check to see if a new LTS release is available. The upgrader
# will attempt to upgrade to the first LTS release available after
# the currently-running one. Note that this option should not be
# used if the currently-running release is not itself an LTS
# release, since in that case the upgrader won't be able to
# determine if a newer release is available.
Prompt=lts
If not, change it to lts and save the file.
Now that your system is ready, run the commands below to begin Ubuntu upgrade to the latest development release…
do-release-upgrade -d
Just follow the instructions!
Mine stopped as I had to fix:
Can not upgrade
Your python install is corrupted. Please fix the '/usr/bin/python' symlink.
That was done via:
ln -sf /usr/bin/python2.7 /usr/bin/python
Once fixed the upgrade process will start - be sure to answer N to the questions about keeping configs. Keep the originals, do not change them!
And yes do remove obsolete files when asked at the end.
Once completed you will be asked to reboot and now the fun begins
The goal to get qb fix version complete without any problems/warnings preferably.
So I started out going for a:
sudo su -
then I saw this screen:
Just to be sure I had no leftovers:
apt -y autoremove && apt -y autoclean
then
apt -y update && apt -y upgrade
then
qb fix dpkg (Yeah using already in place tools to make sure I have no dpkg locks messing up stuff
then
apt -f install mysql-server --reinstall
this fixed the mysql issues I was seing
Then to make sure we still have a woking mariadb this needs to be done:
curl -sS https://downloads.mariadb.com/MariaDB/mariadb_repo_setup | sudo bash
apt -f install mariadb-server --reinstall
Then I did actually ran qb fix version
Grafana was missing so I used qb install grafana
Also showed me a problem with php therefore:
add-apt-repository ppa:ondrej/php
apt update
apt install php7.3-fpm
then nginx was not happy due to the fact it tried to fire up a UB16 version!
so I added a UB18 config for it:
and systemctl restart nginx
then this one spooked around:
nano /etc/php/7.3/cli/php.ini
and remove the mcrypt.so duplicate entries at the bottom!
Then I had a complete success running:
qb fix version
Now head to your website and have a look if everything seems to be running
My rtorrent was dead and so was plex!
Plex was fixed by doing these steps:
- Head to the Plex Downloads page and copy the installation link for Ubuntu. Use wget to download the installer via the copied link:
wget https://downloads.plex.tv/plex-media-server/1.14.1.5488-cc260c476/plexmediaserver_1.14.1.5488-cc260c476_amd64.deb
This example uses the current link for Ubuntu, at the time of writing. Be sure to use the up-to-date version supplied on the Plex website.
Or simply download to your machine and then ftp up in the root folder!
- Use dpkg to install the Plex server:
dpkg -i plexmediaserver*.deb - Enable Plex Media Server to start on reboot, and then start the server:
systemctl enable plexmediaserver.service
systemctl start plexmediaserver.service
then rtorrent problem:
I haven´t had the chance to verify if this was the fix:
then
apt install libcurl4
or if was a reinstall of Ombi that did the trick…
lastly this one came up as I was fixing duplicate entries in the Lock table via phpmyadmin:
phpmyadmin will show phpmyadmin - count(): Parameter must be an array or an object that implements Countable fixed with : nano /usr/share/phpmyadmin/libraries/sql.lib.php jump to line 613 replace || (count($analyzed_sql_results['select_expr'] == 1) with || ((count($analyzed_sql_results['select_expr']) == 1)
This was a rundown of my upgrade to Ubuntu 18.
I know a few steps have been taken to counter a few things with qb fix version but this is all you actually need to get things sorted 
Not that it is an official “we support an upgrade” but just showing its not as frightful as it may sound and you shouldn´t be scared of taking up the task!
With what a little more than a year until dropping security patches and all that for UB16 it is more than likely we will drop support for it at some point.
Feel free to comment or try it out on your own risk but there´s a lot of users on Discord that would be able to help out answering questions related to this.
But don´t expect that an answer can be found straight away as people have different kind of set ups, hosts and kernels so things might or might not be straight forward.
I tried out on a vm box then took on a live box.
/Globber
ps. spelling or grammar errors are free of charge