Версия пакета:
6.6.1.1-alt1

Шаги воспроизведения:
# apt-get install opennebula-server opennebula-sunstone
# systemctl start opennebula

Получаемый результат:
systemd[1]: Starting opennebula.service - OpenNebula Cloud Controller Daemon...
opennebula[12843]: Error while parsing configuration file:
opennebula[12843]: syntax error, unexpected CBRACKET, expecting VARIABLE at line 96, columns 3547:3550
opennebula[12843]: Could not load nebula configuration file.
systemd[1]: opennebula.service: Main process exited, code=exited, status=255/EXCEPTION
opennebula[12847]: /usr/share/one/follower_cleanup:9:in `read': No such file or directory @ rb_sysopen - /var/lib/one/config (Errno::ENOENT)
opennebula[12847]:         from /usr/share/one/follower_cleanup:9:in `<main>'
systemd[1]: opennebula.service: Control process exited, code=exited, status=1/FAILURE
systemd[1]: opennebula.service: Failed with result 'exit-code'.
systemd[1]: Failed to start opennebula.service - OpenNebula Cloud Controller Daemon.

Содержимое 96 строки и рядом в файле /etc/one/oned.conf:
  90   │ VNC_PORTS = [
  91   │     START    = 5900,
  92   │     # RESERVED = "32768:65536"
  93   │     # RESERVED = "6800, 6801, 6810:6820, 9869"
  94   │ ]
  95   │ 
  96   │ #*******************************************************************************
  97   │ # Server network and connection
  98   │ #-------------------------------------------------------------------------------
  99   │ #  PORT: Port where oned will listen for xmlrpc calls.

Решение: убрать запятую из строки "START    = 5900,"