apparently it was the padoka mesa ppa that was blocking the calculation.
Somewhat logical as it's bleeding edge. Purging that ppa fixed the
problem
--
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/1885354
Public bug reported:
On do-release-upgrade -d
After disabling the Third party ppa's I get following messgage:
Berekenen van de opwaardering is mislukt
Er heeft zich een onoplosbaar probleem voorgedaan bij het berekenen
van de upgrade.
Dit komt waarschijnlijk door:
* Onofficiƫle softwarepakke