I don't think you can update from Ubuntu to Xubuntu. But you can simply sudo apt install xubuntu-desktop
to get everything that xubuntu would install.
About your upgrade: (X)Ubuntu 16.04 isn't released yet. You could force the update on the dev version by running sudo do-release-upgrade -d
.
But since you had to ask that, I would recommend holding off another couple of weeks until it's stable. (and then maybe another couple of weeks while the early adopter update :-))
To upgrade from one version to another, first you need to prepare your system, I mean, updating and upgrading. If not, you wont be able to upgrade.
System preparation
Just in case repositories are disabled (if they are, you wont be able to update), go to
Main Menu: System > Administration > Software Sources.
It will display you a window, that must look like this one.
Tick all of em like in the pic!
Now we are going to update the system.
Be sure you have conection to internet, and open a terminal prompt (ctl + alt + T
). Run:
sudo apt-get update
Once updating had finished, let's upgrade the system. In the same terminal prompt run:
sudo apt-get upgrade
Wait until the prompt finishes.
Upgrading to 16.04
If all of this worked without erros, you must be able to upgrade to 16.04. In the same terminal prompt, just run:
sudo do-release-upgrade
Now you can sit and relax, the upgrade will take some time.
Best Answer
New LTS releases are only offered at the first “point release”: 14.04.1, 16.04.1, (probably) 18.04.1, etc. This is done because by then most of the bugs that only show up after a release goes public will be fixed, and people who prefer LTS releases usually prefer a stable system that works without giving them too much trouble.
You can (temporarily) select the option to inform you about all new releases instead of only new LTS releases if you want to be offered an update now. But remember that there might be some issues that affect you still...