problems upgrading from 14.04 to 16.04

[Ralf Mardorf]

On Mon, 26 Sep 2016 19:22:49 +0200, Oliver Grawert wrote:
>hi,
>On Mo, 2016-09-26 at 16:41 +0200, Ralf Mardorf wrote:
>> If a release upgrade should work smoothly, then it must be done
>> without third party, proposed and other experimental repositories
>> enabled or packages installed.
>> 
>> Most likely there's the need to do what Tom suggested, or to do
>> something similar tricky, that hardly could be done automatically.  
>
>automatically disabling PPAs and other third party repos is one of the
>main purposes of do-release-upgrade/update-manager ;) (see [1] if you
>ever want to override this behaviour)
>
>by default all PPAs and unknown repos as well as -proposed get disabled
>before the updater does any actions to the system.
>
>ciao
>	oli
>
>[1] http://bazaar.launchpad.net/~ubuntu-core-dev/ubuntu/xenial/ubuntu-r
>elease-upgrader/xenial/view/head:/DistUpgrade/README#L23

Hi,

ok, I have no time to read the link today. What happens if the OP
already installed packages that aren't from official repositories and
that are very important?

IOW why has got the OP a package installed, that is even a newer
version, than the one available by the release upgraded official repos?
I suspect that only the repos get disabled, but such a package will not
be downgraded, e.g. regarding a dependency chain.

Regards,
Ralf