Those don't look like the log files I'd expected to find in /var/log /dist-upgrade. While main.log is dated Dec 4 it is rather incomplete and apt.log contains information from May 23. Could you double check /var/log/dist-upgrade for main.log, term.log and screenlog.0? Thanks.
** Changed in: ubuntu-release-upgrader (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1257944 Title: release upgrade failed on chrony To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1257944/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs