Further information:
In my case, the situation happened when updating Kubuntu (16.4 to 16.10) from command line using, and after do-release-upgrade crashed during update.
Google adviced me to try apt-get -f install - then the error described above happened.
After retrying "apt-get -f install", "apt-get update", "apt-get upgrade", "apt-get dist-upgrade" a few times, the installation finally completed without errors.
So this bug seems to be a side-effect of another bug in do-release-upgrade .
Further information:
In my case, the situation happened when updating Kubuntu (16.4 to 16.10) from command line using, and after do-release-upgrade crashed during update.
Google adviced me to try apt-get -f install - then the error described above happened.
After retrying "apt-get -f install", "apt-get update", "apt-get upgrade", "apt-get dist-upgrade" a few times, the installation finally completed without errors.
So this bug seems to be a side-effect of another bug in do-release-upgrade .