>     apt-get dist-upgrade is what's necessary to change release - as the name
> means -, eg Wheezy to Jessie or Jessie to Ascii. This is why it should
> rarely be used, and only after carefully editing sources.list. It's a jump
> into the new. Dist-upgrade always worked fine for me and I consider this as
> one of the greatest achievements of Debian's package management technology.

>     I would recommend some clean-up before the jump. For example I would
> uninstall things like mysql server which doesn't recognize any priviledge to
> root. Also Debian tended to install a lot of packages the user doesn't want
> and even doesn't know, so better get them out before the dist-upgrade