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

[Robert Heller]

At Sat, 27 Apr 2019 23:39:02 +0200 "Ubuntu user technical support,  not for general discussions" <ubuntu-users at lists.ubuntu.com> wrote:

> 
> 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).

There was under 14.04 and it was a royal pain in the ass.  When doing updates 
under 14.04, the 'apt-get update' would *often* fail -- not finding the mirror 
and I had to fuss with restarting nscd to solve the problem.

The one 16.04 laptop that I tried to update crashed in do-release-update on 
friday and on my first attempt this morning.  I then noticed that it was 
having a DNS problem.  I manually hacked /etc/resolv.conf and then the upgrade 
went smoothly.  

> 
> 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".

Good to know.  

-- 
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