Comment 27 for bug 619003

I experienced this during the process of upgrading from 13.10 to 14.04 final beta in a terminal window using the command "sudo do-release-upgrade -d". Running the command suggested in the warning message in a console window during and after the upgrade did nothing useful. After completing the upgrade and rebooting there has been no problem and further invocations of apt-get update and apt-get upgrade have gone smoothly.

I did have one failure to boot, the very first reboot after the upgrade it appeared the video wasn't initialized or something. This may be unrelated but I summarize it here just in case. Rebooted again, chose Advanced Options, enabled network, ran dpkg several times to fix broken packages. Rebooted once more to find the wrong video mode, rebooted one final time and everything is running correctly ever since.