I've just installed the Trinity LiveCD

  tde-ubuntu-14.04-desktop-r14.0.3-amd64.iso

and performed all the updates.
I commented out the entries in
/etc/apt/sources.list.d/libreoffice-trinity.list
 -and-
/etc/apt/sources.list.d/trinity.list

and did a sudo do-release-upgrade
to upgrade to xenial (16.04)
and received the following:


|Checking package manager
|Reading package lists... Done
|Building dependency tree
|Reading state information... Done
|Building data structures... Done
|
|Calculating the changes|
|
|Calculating the changes
|
|Could not calculate the upgrade
|
|An unresolvable problem occurred while calculating the upgrade.
|
|This can be caused by:
|* Upgrading to a pre-release version of Ubuntu
|* Running the current pre-release version of Ubuntu
|* Unofficial software packages not provided by Ubuntu
|
|If none of this applies, then please report this bug using the
|command 'ubuntu-bug ubuntu-release-upgrader-core' in a terminal.
|
|Restoring original system state
|
|Aborting

I don't see how any of the "This can be caused by" pertain.

I have done this process successfully with the _32bit_ Trinity LiveCD

Where to start?
Jonesy
-- 
  Marvin L Jones     | Marvin     | W3DHJ  | linux
   Pueblo, Colorado  |  @         | Jonesy |  FreeBSD   __
    38.238N 104.547W |   jonz.net | DM78rf |   OS/2     SK