Comment 2 for bug 1725840

Please attach your upgrade logs from /var/log/dist-upgrade to help us try to see what has happened on your system.

Both before and after the upgrade, /etc/resolv.conf should be a symlink to /run/resolvconf/resolv.conf. If something has replaced that with a file, we would need to figure out what that is. It probably wasn't resolvconf itself.