You seem to have some desktop packages installed but no desktop meta package. Please install one, probably xubuntu-desktop, and try the upgrade again.
2016-01-03 19:39:43,066 DEBUG need_server_mode(): can not find a desktop meta package or key deps, running in server mode
You seem to have some desktop packages installed but no desktop meta package. Please install one, probably xubuntu-desktop, and try the upgrade again.
2016-01-03 19:39:43,066 DEBUG need_server_mode(): can not find a desktop meta package or key deps, running in server mode