muon-updater hangs with "Waiting for configuration file" on debconf question

[Vincas Dargis]

I was upgrading salt-master and salt-minion (installed from their official PPA http://ppa.launchpad.net/saltstack/salt) with muon-updater GUI, but upgrade process stopped on "Waiting for configuration file" status message.

Original bug report with screenshot:
https://github.com/saltstack/salt/issues/23663

Apparently, muon-updater did not produce some kind GUI prompt to answer debconf question:
$ tail -f /var/log/apt/term.log
Configuration file '/etc/salt/master'
 ==> Modified (by you or by a script) since installation.
 ==> Package distributor has shipped an updated version.
   What would you like to do about it ? Your options are:
    Y or I : install the package maintainer's version
    N or O : keep your currently-installed version
      D : show the differences between the versions
      Z : start a shell to examine the situation
 The default action is to keep your current version.
*** master (Y/I/N/O/D/Z) [default=N] ?

To reproduce:

Manually install older slat-minion, salt-common:
https://launchpad.net/~saltstack/+archive/ubuntu/salt2014-7-4/+files/salt-common_2014.7.4%2Bds-1trusty1_all.deb
https://launchpad.net/~saltstack/+archive/ubuntu/salt2014-7-4/+files/salt-minion_2014.7.4%2Bds-1trusty1_all.deb

Also, manually install their dependencies, but do not upgrade salt itself:

$ sudo apt-get -f install dctrl-tools libpgm-5.1-0 libzmq3 python-m2crypto python-msgpack python-yaml python-zmq

Then, change /etc/salt/minion line:
#master: salt
into
master: salt

Then, open muon-updater, check for available updates and proceed installing latest salt-minion. Installation will not finish.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: muon-updater 2.2.0-0ubuntu3.2
ProcVersionSignature: Ubuntu 3.16.0-38.52~14.04.1-generic 3.16.7-ckt10
Uname: Linux 3.16.0-38-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.14.1-0ubuntu3.11
Architecture: amd64
CurrentDesktop: KDE
Date: Fri May 29 18:38:58 2015
InstallationDate: Installed on 2013-12-05 (539 days ago)
InstallationMedia: Kubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
SourcePackage: muon
UpgradeStatus: Upgraded to trusty on 2014-05-04 (389 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[A. Fachat (fachat)]

Can confirm this. I ran into this problem when updating squid. Muon was waiting for configuration file, and nothing else happened. Then found this report and looked at term.log:

sudo tail /var/log/apt/term.log
Configuration file '/etc/squid3/squid.conf'
 ==> Modified (by you or by a script) since installation
 ==> Package distributor has shipped an updated version.
     What would you like to do about it ? Your options are:
     Y or I : install the package maintainer's version
     N or 0 : keep your currently-installed version
         D : show the differences between the versions
         Z : start a shell to examine the situation
    The default action is to keep your current version
*** squid.conf (Y/I/N/0/D/Z) [default=N] ?

[apsaras (c-launchpad1)]

I encountered the same problem trying to update a package (exim4 as it happens) whose configuration file I had previous modified. muon-updater just hung "Waiting for configuration file". muon-updater didn't provide a way to exit it cleanly, so I ended up killing it externally. Then had to kill two qaptworker2 processes so that the lock on the package database was released. Then

$ sudo dpkg --configure -a

completed the update.

[Ansgar-radermacher (ansgar-radermacher)]

Getting the same problem right now, apt update is blocked. term shows:

sudo tail /var/log/apt/term.log
Configuration file '/etc/sudoers'
 ==> Modified (by you or by a script) since installation.
 ==> Package distributor has shipped an updated version.
   What would you like to do about it ? Your options are:
    Y or I : install the package maintainer's version
    N or O : keep your currently-installed version
      D : show the differences between the versions
      Z : start a shell to examine the situation
 The default action is to keep your current version.

[Chris (achrislong+ubuntu)]

Ran into this for docker-engine. Worked around it thanks to https://bugs.launchpad.net/ubuntu/+source/muon/+bug/1460133/comments/4