Comment 29 for bug 1712283

@diabloneo

resolvconf doesn't leave a process running on the system; it is only triggered when there are changes to the network or to the available local resolvers, and coordinates updates to /etc/resolv.conf.

But if /etc/resolv.conf is not a symlink to /run/resolvconf/resolv.conf, this has no effect.

And if NetworkManager had written its own contents to /etc/resolv.conf, that means either it was not a symlink to /run/resolvconf/resolv.conf, or you were using a buggy version of NetworkManager. (The Ubuntu package of NetworkManager detects when resolvconf is in use, and avoids overwriting /etc/resolv.conf.)

The question is how your system got into that state in 17.04. But this may not be a question we are able to answer after the fact.

If you have any further insight into how your system got into this state, we would be interested to know. Otherwise, I recommend you follow Dimitri's guidance from comment #27 to return your system into a supported configuration.