How Come I Cannot Download the Latest Ubuntu 15.04 Desktop?

[Colin Law]

On 8 August 2015 at 15:57, Tom H <tomh0665 at gmail.com> wrote:
> On Sat, Aug 8, 2015 at 7:19 AM,  <silver.bullet at zoho.com> wrote:
>> On Sat, 8 Aug 2015 11:08:55 +0100, Colin Law wrote:
>>>
>>>To upgrade from 14.04 to 15.04 you do not need the 15.04 image.  There
>>>should be an option in the Software Updater to do it, or you can do,
>>>in a terminal
>>>sudo do-release-upgrade
>>
>> By hearsay a release upgrade could break even a well maintained install
>> based on official repositories only. At least developers of an Ubuntu
>> flavour once claimed this. Assumed a release upgrade for a well
>> maintained install based on official repositories only should never
>> cause trouble, I suspect that when using third party repositories
>> it could break an install.
>
> Doesn't do-release-upgrade disable all ppas and otehr non-standard repos?

It has to  as it has no way of knowing whether stuff there is
compatible with the later distro.
In fact I think it is safer to manually purge any ppas before
upgrading, using ppa-purge, I think that decreases the likelihood of
problems during upgrade.
I also uninstall any stuff that I installed from deb files or that are
no longer in the repos, a list of these can be found in Synaptic by
selecting Status then Installed(local or obsolete).  You can
re-install these after the upgrade if you still need them (assuming
they are still available).  Config files will not have been deleted so
it should be a simple matter to re-install them.
When I have done both the above I believe I have never had significant
problems with an upgrade.

Colin