do-release-upgrade is crashing when going from 16.04 to 18.04

[Tom H]

On Sat, Apr 27, 2019 at 5:46 PM Robert Heller <heller at deepsoft.com> wrote:
> At Fri, 26 Apr 2019 16:40:32 -0400 (EDT) Robert Heller <heller at deepsoft.com> wrote:
>>
>> I recently upgraded a laptop from 14.04 to 16.04 using
>> do-release-upgrade. I has been running just fine with 16.04, but I
>> just tried to update it to 18.04 by running do-release-upgrade
>> again, but do-release-upgrade is crashing.
>>
>> The only *possible* weirdness is that I am using a local mirror
>> (built with debmirror). I did use this mirror to install a 18.04 VM
>> (and have been successfully keeping the VM up-to-date). And I did
>> use the mirror to upgrade this laptop, another laptop, and (so far)
>> one desktop machine from 14.04 to 16.04.
>>
>> What should I be looking for to debug this problem?
>
> OK, I retried this and determined that it was the stupid damn
> cacheing nameserver Ubuntu insists upon installing. I'd just as soon
> just use the "real" (bind9) nameserver running on the server on the
> LAN. So how to I get rid of the cacheing nameserver -- would just
> doing 'apt-get purge nscd' work?

There's no nscd (by default anyway).

It's most probably systemd-networkd. Make it use your LAN's nameserver
either by editing "/etc/systemd/resolved.conf" or by creating
"/etc/systemd/resolved.conf.d/foo.conf".