I have been playing a bit and did a fully manual update to 1604:
1.0) disable any third party packages in /etc/apt/source.list.d/
1.1) in /etc/apt/source.list change "wily" to "xenial" throughout
2.) apt-get update
3.) apt-get install base-file dpkg systemd
4.) apt-get dist-upgrade
5.) and it works!
I have been playing a bit and did a fully manual update to 1604: source. list.d/ source. list change "wily" to "xenial" throughout
1.0) disable any third party packages in /etc/apt/
1.1) in /etc/apt/
2.) apt-get update
3.) apt-get install base-file dpkg systemd
4.) apt-get dist-upgrade
5.) and it works!