Para resgatar minha reputação, fiz mais algumas pesquisas e tentei algumas coisas com meu servidor. Depois de fazer o seguinte, não recebo mais a mensagem de erro e meu servidor parece estar se comportando normalmente. Usei esta página SystemdForUpstartUsers para obter orientação.
O que ele fez não tenho idéia, mas parece funcionar. Sinto que Upstart e Systemd são conflitantes. Ao forçar a instalação do Systemd, o Upstart é removido.
apt-get --force-yes install systemd-sysv ubuntu-standard
update-initramfs -u
aqui está a minha saída:
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
ubuntu-minimal upstart ureadahead
The following NEW packages will be installed:
systemd-sysv ubuntu-standard
0 upgraded, 2 newly installed, 3 to remove and 0 not upgraded.
Need to get 8,548 B/11.4 kB of archives.
After this operation, 723 kB disk space will be freed.
Do you want to continue? [Y/n]
WARNING: The following packages cannot be authenticated!
systemd-sysv ubuntu-standard
Install these packages without verification? [y/N] y
Get:1 http://us.archive.ubuntu.com/ubuntu/ utopic-updates/universe systemd-sysv amd64 208-8ubuntu8.2 [8,548 B]
Fetched 8,548 B in 4s (2,042 B/s)
(Reading database ... 132103 files and directories currently installed.)
Removing ubuntu-minimal (1.327) ...
Removing ureadahead (0.100.0-16) ...
dpkg: upstart: dependency problems, but removing anyway as you requested:
friendly-recovery depends on upstart | systemd-sysv; however:
Package upstart is to be removed.
Package systemd-sysv is not installed.
Removing upstart (1.13.2-0ubuntu2) ...
Processing triggers for man-db (2.7.0.2-2) ...
Selecting previously unselected package systemd-sysv.
(Reading database ... 132056 files and directories currently installed.)
Preparing to unpack .../systemd-sysv_208-8ubuntu8.2_amd64.deb ...
Unpacking systemd-sysv (208-8ubuntu8.2) ...
Selecting previously unselected package ubuntu-standard.
Preparing to unpack .../ubuntu-standard_1.327_amd64.deb ...
Unpacking ubuntu-standard (1.327) ...
Processing triggers for man-db (2.7.0.2-2) ...
Espero que isso ajude alguém.