Question is about Ubuntu release process. Are migrations from n to n+1 releases expected?
Assuming we have server with installed Ubuntu 14.04 LTS. Will it be smoothly upgradable to Ubuntu 16.04 LTS via apt-get upgrade ?
Assumptions:
You can upgrade smoothly through LTS releases whether it's Server or Desktop. It doesn't matter what you use, you just need to use these commands:
For Desktop Version:
sudo do-release-upgrade
For Server Version:
sudo apt-get install update-manager-core
sudo do-release-upgrade
NOTE: Please always make sure you test the target LTS you're being prompted to upgrade to in a LiveCD on the machine you're using to make sure everything works properly before going in for the real upgrade itself.
Yes, you can upgrade from one Ubuntu LTS version to the next one, skipping the non-LTS releases in-between. It's intended to work that way and it gets tested.
I trusted other answers and proceeded to the upgrade from an up-to-date 14.04 to 16.04 using do-release-upgrade. Now I am facing a kernel panic.
Here are other relevant questions (not mine), most unanswered :
Therefore the actual answer to the question "can I smoothly upgrade from one LTS to next LTS release", in particular when applied to 14.04->16.04 upgrade as suggested in the OP, is clearly not "yes" — and most if not all answers are wrong in this regard.
At best, you might smoothly upgrade.
You can upgrade from one LTS version to another. If its smooth or not depends.
If you're referring only to the OS, the process is tested and if your hardware is compatible everything will be fine.
Don't forget though that you may have your own software/scripts/etc installed or other configurations that may have unmet dependencies in the new version. (eg.: you have some script with deprecated functions that are dropped in a newer version)
Upgrades from 14.04 to 16.04 are not automatically when 16.04 comes out in April but in July the first point release 16.04.1 will become available and all 14.04 users will be offered the upgrade then.
However, if you want to upgrade immediately, you do NOT need to upgrade to an intermediate release first. Just run the following in a terminal (and type your password):
sudo update-manager -d
You will then be offered the 14.04 -> 16.04 upgrade without waiting for 16.04.1.
The reason Ubuntu doesn't automatically offer 16.04 to 14.04 users is simple: those users are using a very stable LTS release, and might hit undiscovered bugs in 16.04 if they upgraded immediately at release. Any important bugs found in 16.04 should be fixed by the 16.04.1 point release, so LTS users have less chance of running into bugs in the new release.
Just a quick note on upgrading from an old non-LTS release: I was stuck on 13.04 (Raring Ringtail, non-LTS), and wanted to upgrade. First get up to 14.04 LTS (Trusty Tahr), then upgrade to 16.04 (Xenial Xerus).
To upgrade from 13.04 (in September 2016!), you need some hacking, and this guy had a way: http://tuxtrix.com/2014/03/upgrade-from-ubuntu-1304-to-ubuntu-1404.html
It worked for me!
(Tip: Run the upgrade in Console (ctrl+alt+F1), not in the desktop GUI. While upgrading, X or whatever hung on me, and I had to hammer a bit to get it through..)
Yes you can. a step by step guide. https://www.digitalocean.com/community/tutorials/how-to-upgrade-to-ubuntu-16-04-lts
It can be difficult and confusing to select the version of Ubuntu both for the first installation and for upgrading to a new released version. This answer will focus on how to find the version with the longest remaining support time (until 'end of life'), which is often the first point release of an LTS release (LTS stands for Long Time Support).
Right now, when this is written, it is Ubuntu 16.04.1 LTS, and its iso files are not found via the 'usual' links for the current versions.
The support intervals are described with details and diagrams in this link,
www.ubuntu.com/info/release-end-of-life
The kernel series of the second, third and fourth point releases are different from the kernel series of the first point release, and are not supported for a long time. The hardware enablement stack must/will be upgraded according to these links,
wiki.ubuntu.com/Kernel/LTSEnablementStack
wiki.ubuntu.com/Kernel/RollingLTSEnablementStack
in order to keep everything up to date (including security updates of the kernel). This is risky and I would discourage you to do that. Many failures are reported. Some of these problems can be found, if you type HWE into the 'Search Q&A' window near the top right corner of the web browser's window with AskUbuntu (and press Enter).
The kernel series of the fifth point release is that of the next LTS relesase and has long support.
I would recommend the following strategy, if you want to use a stable and reliable system.
A good backup routine for all files, that you want to keep, is the fundament of a stable and reliable system. This includes your personal files and the whole or parts of the operating system and installed application programs and tweaks.
Install and stay with LTS releases that are released in April during even years, 2014, 2016, 2018, ...
Install the version which has the longest time until end of life right now. Test it and if it works well, stay with it. "If it ain't broke, don't fix it"
Stay with update & upgrade within the kernel series
sudo apt update
sudo apt full-upgrade
When the next first point release is released, wait for a month, and sometime late in August, the worst bugs are fixed, and you can install the new release and do the updates & upgrades to a well debugged and polished system. This can mean changing
It is often better to install a fresh system and after that copy your personal files from the old system to the new system. It is possible to upgrade from the old LTS release to the next LTS release via
sudo do-release-upgrade
but it is risky, and you had better get a fresh backup before trying it.
Start looking for the iso files of the version with the longest remaining support via these links,
If the iso files of the version with the longest remaining support are not found via those links, you can find them via the following general link,
and right now, when this is written, you want to find Ubuntu 16.04.1 LTS via the following link,
If you want to upgrade from 12.04 LTS to 16.04 LTS, you can't do that. You can't skip an LTS release like that. You need to update 12.04->14.04 and then 14.04->16.04.
It will probably be quicker to just do a reinstall (and setting up your server so it'll be easier next time ;) ).
Yes, you can smoothly and easily upgrade from one LTS to next LTS release:
Step Press Alt + F2 and type update-manager and then follow the onscreen instructions.
