problems upgrading from 14.04 to 16.04

[Ralf Mardorf]

As long as the package index files aren't upgraded apt --fix-broken
can't resolve issues.

Regarding the official repositories, try another mirror:
http://askubuntu.com/questions/39922/how-do-you-select-the-fastest-mirror-from-the-command-line

Regarding the third party repository:
A wild guess, perhaps 32 bit support was dropped in the meantime and
related to this, they maybe dropped the repository for 64 bit, too. You
should send a request to the third party support, since this isn't an
Ubuntu related question.

Regards,
Ralf