This is the /var/log/dist-upgrade/apt.log file which contains information about the failure to upgrade.
** Attachment added: "apt.log" https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1726180/+attachment/4994716/+files/apt.log -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1726180 Title: Unable to run do-release-upgrade To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1726180/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs