After installing some updates my OpenVPN client was suddenly unable to resolve any host names. The following output was observed when attempting to connect:

Warning: resolvconf: Error: /etc/resolv.conf must be a symlink

Examining /etc/resolv.conf indicated the file was not being updated as expected. One of the updates must have broken the symlink/configuration. I was able to resolve the issue by running:

$ dpkg-reconfigure resolvconf

Executing this command runs a reconfiguration script which backs up the original /etc/resolv.conf file and creates a new dynamic symlink resolving this issue.