Tested with 1.1ubuntu1.18.04.7~16.04.1: $ sudo chroot x-test-1803749/ root@MacBookAir-test:/# apt install unattended-upgrades zsh Reading package lists... Done Building dependency tree... Done The following additional packages will be installed: iso-codes python-apt-common python3-apt xz-utils zsh-common Suggested packages: isoquery python3-apt-dbg python-apt-doc bsd-mailx mail-transport-agent zsh-doc The following NEW packages will be installed: iso-codes python-apt-common python3-apt unattended-upgrades xz-utils zsh zsh-common 0 upgraded, 7 newly installed, 0 to remove and 0 not upgraded. Need to get 6354 kB of archives. After this operation, 32.2 MB of additional disk space will be used. Do you want to continue? [Y/n] Get:1 http://archive.ubuntu.com/ubuntu xenial/main amd64 zsh-common all 5.1.1-1ubuntu2 [3170 kB] Get:2 http://archive.ubuntu.com/ubuntu xenial/main amd64 zsh amd64 5.1.1-1ubuntu2 [651 kB] Get:3 http://archive.ubuntu.com/ubuntu xenial/main amd64 iso-codes all 3.65-1 [2268 kB] Get:4 http://archive.ubuntu.com/ubuntu xenial/main amd64 python-apt-common all 1.1.0~beta1build1 [17.3 kB] Get:5 http://archive.ubuntu.com/ubuntu xenial/main amd64 python3-apt amd64 1.1.0~beta1build1 [137 kB] Get:6 http://archive.ubuntu.com/ubuntu xenial/main amd64 xz-utils amd64 5.1.1alpha+20120614-2ubuntu2 [78.8 kB] Get:7 http://archive.ubuntu.com/ubuntu xenial/main amd64 unattended-upgrades all 0.90 [31.6 kB] Fetched 6354 kB in 6s (1024 kB/s) Preconfiguring packages ... E: Can not write log (Is /dev/pts mounted?) - posix_openpt (19: No such device) Selecting previously unselected package zsh-common. (Reading database ... 10444 files and directories currently installed.) Preparing to unpack .../zsh-common_5.1.1-1ubuntu2_all.deb ... Unpacking zsh-common (5.1.1-1ubuntu2) ... Selecting previously unselected package zsh. Preparing to unpack .../zsh_5.1.1-1ubuntu2_amd64.deb ... Unpacking zsh (5.1.1-1ubuntu2) ... Selecting previously unselected package iso-codes. Preparing to unpack .../iso-codes_3.65-1_all.deb ... Unpacking iso-codes (3.65-1) ... Selecting previously unselected package python-apt-common. Preparing to unpack .../python-apt-common_1.1.0~beta1build1_all.deb ... Unpacking python-apt-common (1.1.0~beta1build1) ... Selecting previously unselected package python3-apt. Preparing to unpack .../python3-apt_1.1.0~beta1build1_amd64.deb ... Unpacking python3-apt (1.1.0~beta1build1) ... Selecting previously unselected package xz-utils. Preparing to unpack .../xz-utils_5.1.1alpha+20120614-2ubuntu2_amd64.deb ... Unpacking xz-utils (5.1.1alpha+20120614-2ubuntu2) ... Selecting previously unselected package unattended-upgrades. Preparing to unpack .../unattended-upgrades_0.90_all.deb ... Unpacking unattended-upgrades (0.90) ... Processing triggers for ureadahead (0.100.0-19) ... Processing triggers for systemd (229-4ubuntu4) ... Setting up zsh-common (5.1.1-1ubuntu2) ... Setting up zsh (5.1.1-1ubuntu2) ... update-alternatives: using /bin/zsh5 to provide /bin/zsh (zsh) in auto mode update-alternatives: using /bin/zsh5 to provide /bin/rzsh (rzsh) in auto mode Setting up iso-codes (3.65-1) ... Setting up python-apt-common (1.1.0~beta1build1) ... Setting up python3-apt (1.1.0~beta1build1) ... Setting up xz-utils (5.1.1alpha+20120614-2ubuntu2) ... update-alternatives: using /usr/bin/xz to provide /usr/bin/lzma (lzma) in auto mode Setting up unattended-upgrades (0.90) ... Creating config file /etc/apt/apt.conf.d/20auto-upgrades with new version Creating config file /etc/apt/apt.conf.d/50unattended-upgrades with new version update-rc.d: warning: start and stop actions are no longer supported; falling back to defaults Processing triggers for ureadahead (0.100.0-19) ... Processing triggers for systemd (229-4ubuntu4) ... root@MacBookAir-test:/# apt-mark auto zsh zsh set to automatically installed. root@MacBookAir-test:/# echo "Unattended-Upgrade::Package-Blacklist {"libs";}" > /etc/apt/apt.conf.d/51unattended-upgrades root@MacBookAir-test:/# echo "deb http://archive.ubuntu.com/ubuntu xenial-security main" >> /etc/apt/sources.list root@MacBookAir-test:/# echo "deb http://archive.ubuntu.com/ubuntu xenial-updates main" >> /etc/apt/sources.list root@MacBookAir-test:/# apt update -qq 105 packages can be upgraded. Run 'apt list --upgradable' to see them. root@MacBookAir-test:/# unattended-upgrades --dry-run --verbose --debug Initial blacklisted packages: libs Initial whitelisted packages: Starting unattended upgrades script ... adjusting candidate version: 'libkmod2=22-1ubuntu5' adjusting candidate version: 'libstdc++6=5.4.0-6ubuntu1~16.04.10' adjusting candidate version: 'sudo=1.8.16-0ubuntu1.4' marking zsh-common for remove marking zsh for remove Packages that are auto removed: 'zsh zsh-common' E: Can not write log (Is /dev/pts mounted?) - posix_openpt (19: No such device) /usr/bin/dpkg --status-fd 197 --force-depends --force-remove-essential --remove zsh:amd64 zsh-common:all /usr/bin/dpkg --status-fd 199 --configure --pending Packages were successfully auto-removed InstCount=0 DelCount=2 BrokenCount=0 root@MacBookAir-test:/# echo "deb http://archive.ubuntu.com/ubuntu xenial-proposed main" >> /etc/apt/sources.list root@MacBookAir-test:/# apt update -qq 105 packages can be upgraded. Run 'apt list --upgradable' to see them. root@MacBookAir-test:/# root@MacBookAir-test:/# apt install unattended-upgrades Reading package lists... Done Building dependency tree Reading state information... Done The following additional packages will be installed: dbus gir1.2-glib-2.0 libcap-ng0 libdbus-1-3 libdbus-glib-1-2 libgirepository-1.0-1 libglib2.0-0 libglib2.0-data libicu55 libxml2 powermgmt-base python3-dbus python3-gi sgml-base shared-mime-info xdg-user-dirs xml-core Suggested packages: dbus-user-session | dbus-x11 python-dbus-doc python3-dbus-dbg sgml-base-doc bsd-mailx default-mta | mail-transport-agent needrestart debhelper The following NEW packages will be installed: dbus gir1.2-glib-2.0 libcap-ng0 libdbus-1-3 libdbus-glib-1-2 libgirepository-1.0-1 libglib2.0-0 libglib2.0-data libicu55 libxml2 powermgmt-base python3-dbus python3-gi sgml-base shared-mime-info xdg-user-dirs xml-core The following packages will be upgraded: unattended-upgrades 1 upgraded, 17 newly installed, 0 to remove and 104 not upgraded. Need to get 11.0 MB of archives. After this operation, 43.5 MB of additional disk space will be used. Do you want to continue? [Y/n] Get:1 http://archive.ubuntu.com/ubuntu xenial-security/main amd64 libglib2.0-0 amd64 2.48.2-0ubuntu4.1 [1120 kB] Get:2 http://archive.ubuntu.com/ubuntu xenial/main amd64 sgml-base all 1.26+nmu4ubuntu1 [12.5 kB] Get:3 http://archive.ubuntu.com/ubuntu xenial/main amd64 libcap-ng0 amd64 0.7.7-1 [10.9 kB] Get:4 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 libdbus-1-3 amd64 1.10.6-1ubuntu3.3 [161 kB] Get:5 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 dbus amd64 1.10.6-1ubuntu3.3 [142 kB] Get:6 http://archive.ubuntu.com/ubuntu xenial/main amd64 libgirepository-1.0-1 amd64 1.46.0-3ubuntu1 [88.3 kB] Get:7 http://archive.ubuntu.com/ubuntu xenial/main amd64 gir1.2-glib-2.0 amd64 1.46.0-3ubuntu1 [127 kB] Get:8 http://archive.ubuntu.com/ubuntu xenial/main amd64 libdbus-glib-1-2 amd64 0.106-1 [67.1 kB] Get:9 http://archive.ubuntu.com/ubuntu xenial-security/main amd64 libglib2.0-data all 2.48.2-0ubuntu4.1 [132 kB] Get:10 http://archive.ubuntu.com/ubuntu xenial-security/main amd64 libicu55 amd64 55.1-7ubuntu0.4 [7646 kB] Get:11 http://archive.ubuntu.com/ubuntu xenial-security/main amd64 libxml2 amd64 2.9.3+dfsg1-1ubuntu0.6 [697 kB] Get:12 http://archive.ubuntu.com/ubuntu xenial/main amd64 powermgmt-base all 1.31+nmu1 [7178 B] Get:13 http://archive.ubuntu.com/ubuntu xenial/main amd64 python3-dbus amd64 1.2.0-3 [83.1 kB] Get:14 http://archive.ubuntu.com/ubuntu xenial/main amd64 python3-gi amd64 3.20.0-0ubuntu1 [153 kB] Get:15 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 shared-mime-info amd64 1.5-2ubuntu0.2 [405 kB] Get:16 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 xdg-user-dirs amd64 0.15-2ubuntu6.16.04.1 [61.8 kB] Get:17 http://archive.ubuntu.com/ubuntu xenial/main amd64 xml-core all 0.13+nmu2 [23.3 kB] Get:18 http://archive.ubuntu.com/ubuntu xenial-proposed/main amd64 unattended-upgrades all 1.1ubuntu1.18.04.7~16.04.1 [40.2 kB] Fetched 11.0 MB in 6s (1827 kB/s) ... Processing triggers for sgml-base (1.26+nmu4ubuntu1) ... root@MacBookAir-test:/# unattended-upgrades --dry-run --verbose --debug Initial blacklisted packages: libs ... applying set ['python3.5', 'python3.5-minimal', 'libpython3.5-stdlib', 'libpython3.5-minimal'] apt_pkg.pkgsystem_unlock() failed due to not holding the lock but trying to continue E: Can not write log (Is /dev/pts mounted?) - posix_openpt (19: No such device) /usr/bin/dpkg --status-fd 139 --unpack --auto-deconfigure /var/cache/apt/archives/python3.5_3.5.2-2ubuntu0~16.04.5_amd64.deb /var/cache/apt/archives/libpython3.5-stdlib_3.5.2-2ubuntu0~16.04.5_amd64.deb /var/cache/apt/archives/python3.5-minimal_3.5.2-2ubuntu0~16.04.5_amd64.deb /var/cache/apt/archives/libpython3.5-minimal_3.5.2-2ubuntu0~16.04.5_amd64.deb /usr/bin/dpkg --status-fd 141 --configure libpython3.5-minimal:amd64 python3.5-minimal:amd64 libpython3.5-stdlib:amd64 python3.5:amd64 /usr/bin/dpkg --status-fd 143 --configure --pending left to upgrade set() All upgrades installed InstCount=0 DelCount=0 BrokenCount=0 root@MacBookAir-test:/#