Binary package hint: debconf
Upgrading Kubuntu Feisty to Gutsy Beta in the way described here https://help.ubuntu.com/community/GutsyUpgrades works until adept begins to install downloaded packages. Terminal in adept doesn't say anything, just pops up window with error message that package "debconf" cannot be corectly installed. After click 'continue' next two packages 'xorg-common' and 'xorg-x11...' declare the same error. Then upgrade freezes. Only way is KILL it. Problem continues thru 'unable to lock the administration directory (/var/lib/dpkg/)' and final are packages which has adept (during upgrade) already installed:
kde4games-data, kdelibs5-data, libaudiofile-dev, libavahi-client-dev, libavahi-common-dev, libavahi-glib-dev, libebook1.2-9, libedata-book1.2-2, libgcrypt11-dev, libgnomevfs2-dev, libgnutls-dev, libgpg-error-dev, liblzo-dev, libopencdk8-dev, libraptor1, librasqal0, librdf0, libselinux1-dev, libsepol1-dev, libsoprano3, libstreamanalyzer0, libstreams0, libtasn1-3-dev.
Solved: after all REBOOT -> X crashed down -> cp backup/sources.list.bcp.fiesty /etc/apt/sources.list -> apt-get update -> dpkg --configure -a -> apt-get upgrade; apt-get autoremove -> restart x
The solved is ok, but cp etc/apt/