Comment 20 for bug 1646739

This happened to me yesterday on a 16.04 desktop system using update-manager. Apparently failed during setup of package unattended-upgrades.

Below is apt/history.log, apt/term.log, ps and debconf version taken while the GUI has been hanging (greyed out and unresponsive) for ~15 hours. GUI screenshot as shown in attachment.

$ tail -4 /var/log/apt/history.log
Start-Date: 2017-05-20 21:12:22
Commandline: aptdaemon role='role-commit-packages' sender=':1.438'
Upgrade: iproute:amd64 (1:4.3.0-1ubuntu3, 1:4.3.0-1ubuntu3.16.04.1), iproute2:amd64 (4.3.0-1ubuntu3, 4.3.0-1ubuntu3.16.04.1), unattended-upgrades:amd64 (0.90ubuntu0.5, 0.90ubuntu0.6), libjasper1:amd64 (1.900.1-debian1-2.4ubuntu1, 1.900.1-debian1-2.4ubuntu1.1)
End-Date: 2017-05-20 21:12:29

$ tail -23 /var/log/apt/term.log
Log started: 2017-05-20 21:12:22
(Reading database ... 359114 files and directories currently installed.)
Preparing to unpack .../iproute2_4.3.0-1ubuntu3.16.04.1_amd64.deb ...
Unpacking iproute2 (4.3.0-1ubuntu3.16.04.1) over (4.3.0-1ubuntu3) ...
Preparing to unpack .../iproute_1%3a4.3.0-1ubuntu3.16.04.1_all.deb ...
Unpacking iproute (1:4.3.0-1ubuntu3.16.04.1) over (1:4.3.0-1ubuntu3) ...
Preparing to unpack .../libjasper1_1.900.1-debian1-2.4ubuntu1.1_amd64.deb ...
Unpacking libjasper1:amd64 (1.900.1-debian1-2.4ubuntu1.1) over (1.900.1-debian1-2.4ubuntu1) ...
Preparing to unpack .../unattended-upgrades_0.90ubuntu0.6_all.deb ...
Unpacking unattended-upgrades (0.90ubuntu0.6) over (0.90ubuntu0.5) ...
Processing triggers for man-db (2.7.5-1) ...
Processing triggers for libc-bin (2.23-0ubuntu7) ...
Processing triggers for systemd (229-4ubuntu17) ...
Processing triggers for ureadahead (0.100.0-19) ...
Setting up iproute2 (4.3.0-1ubuntu3.16.04.1) ...
Setting up iproute (1:4.3.0-1ubuntu3.16.04.1) ...
Setting up libjasper1:amd64 (1.900.1-debian1-2.4ubuntu1.1) ...
Setting up unattended-upgrades (0.90ubuntu0.6) ...
Use of uninitialized value $_[1] in join or string at /usr/share/perl5/Debconf/DbDriver/Stack.pm line 111, <GEN0> line 12.
Use of uninitialized value $val in substitution (s///) at /usr/share/perl5/Debconf/Format/822.pm line 83, <GEN7> line 11.
Use of uninitialized value $val in concatenation (.) or string at /usr/share/perl5/Debconf/Format/822.pm line 84, <GEN7> line 11.
Processing triggers for libc-bin (2.23-0ubuntu7) ...
Log ended: 2017-05-20 21:12:29

$ ps aux |grep update
miki 5027 0.0 1.2 730908 95960 ? Sl May20 0:20 /usr/bin/python3 /usr/bin/update-manager
miki 10100 0.0 0.2 591036 22164 ? Sl May20 0:01 update-notifier

$ dpkg -l|grep debconf |head -1
ii debconf 1.5.58ubuntu1 all Debian configuration management system

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04.2 LTS
Release: 16.04
Codename: xenial