Upgrade from 10.04 to 12.04 fails

Tried to upgrade from Ubuntu 10.04 LTS to 12.04 LTS failed. There were some messages about conflicts in update manager window, followed by a short traceback from logger (closed file/io err), but that window was not selectable because of the pop-up window.

Tried to do the update from command line with do-release-upgrade. It has issues with locale (lv).. it asks "Continue [iN]", but acepts only j (not y and not i). Anyhow, got the output:
Aprēķina izmaiņas

Aprēķina izmaiņas

Vai vēlaties sākt uzlabošanu?

Canonical vairs neatbalsta 29 instalētas pakotnes. Vēl aizvien var
dabūt atbalstu no kopienas.

86 pakotnes tiks noņemtas. 932 pakotnes tiks instalētas. 1021
pakotne tiks uzlabota.

Atjauninājumu saņemšana un instalēšana var aizņemt vairākas
stundas. Kolīdz lejupielāde ir pabeigta, atjauninājumu
instalēšanu vairs nevar atcelt.

 Turpināt [iN] Sīkāka informācija [d]j
 Turpināt [iN] Sīkāka informācija [d]j

Iegūst
Fetched 0 B in 0s (0 B/s)

Uzlabo
start: Job is already running: apport
Fetched 0 B in 0s (0 B/s)
    libdrm-nouveau1a:amd64 conflicts with libdrm-nouveau1:amd64
        gvfs-libs:amd64 conflicts with libgvfscommon0:amd64
  python-desktopcouch-records:amd64 conflicts with desktopcouch:amd64
Exception during pm.DoInstall(): E:Internal Error, Could not early remove desktopcouch:amd64 (1)
Could not import module, is a package upgrade in progress? Error: No module named launchpadlib.errors

Neizdevās instalēt uzlabojumus

Uzlabošana ir pārtraukta. Sistēma varētu būt nelietojamā
stāvoklī. Tagad tiks veikta atgūšanās (dpkg --configure -a).

Please report this bug in a browser at
http://bugs.launchpad.net/ubuntu/+source/update-manager/+filebug and
attach the files in /var/log/dist-upgrade/ to the bug report.
E:Internal Error, Could not early remove desktopcouch:amd64 (1)

Uzlabošana pabeigta

Uzlabošana ir pabeigta, bet tās laikā bija kļūdas.

I have no idea how to resolve this.