Looking at .var.apt.history.log.txt we can see that in a previous package operation linux-generic was removed.
Start-Date: 2018-08-14 13:37:10 Commandline: apt dist-upgrade Install: linux-headers-4.15.0-32-generic:amd64 (4.15.0-32.35, automatic), linux-headers-4.15.0-32:amd64 (4.15.0-32.35, automatic) Upgrade: linux-headers-generic:amd64 (4.15.0.31.33, 4.15.0.32.34), linux-libc-dev:amd64 (4.15.0-31.33, 4.15.0-32.35) Remove: linux-signed-generic:amd64 (4.15.0.31.33), linux-generic:amd64 (4.15.0.31.33) End-Date: 2018-08-14 13:37:16 Subsequently during the unattended-upgrades run linux-image-generic is identified as an unused package. I'm only able to recreate this if I first remove the linux-generic package e.g.: bdmurray@clean-bionic-amd64:~$ sudo apt remove linux-generic [sudo] password for bdmurray: Reading package lists... Done Building dependency tree Reading state information... Done The following packages were automatically installed and are no longer required: amd64-microcode intel-microcode iucode-tool linux-headers-generic linux-image-generic thermald Use 'sudo apt autoremove' to remove them. The following packages will be REMOVED: linux-generic 0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded. After this operation, 15.4 kB disk space will be freed. Do you want to continue? [Y/n] Y (Reading database ... 165999 files and directories currently installed.) Removing linux-generic (4.15.0.30.32) ... bdmurray@clean-bionic-amd64:~$ sudo unattended-upgrades -v Initial blacklisted packages: Initial whitelisted packages: Starting unattended upgrades script Allowed origins are: o=Ubuntu,a=bionic, o=Ubuntu,a=bionic-security, o=UbuntuESM,a=bionic Removing unused kernel packages: linux-headers-generic linux-image-generic (Reading database ... 165996 files and directories currently installed.) Removing linux-headers-generic (4.15.0.30.32) ... (Reading database ... 165993 files and directories currently installed.) Removing linux-image-generic (4.15.0.30.32) ... Packages that were successfully auto-removed: linux-headers-generic linux-image-generic Packages that are kept back: No packages found that can be upgraded unattended and no pending auto-removals -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to unattended-upgrades in Ubuntu. https://bugs.launchpad.net/bugs/1787460 Title: Unattended upgrades removed linux-image-generic Status in unattended-upgrades package in Ubuntu: New Bug description: On a fairly fresh install of 18.04 with no modifications whatsoever to the unattended-upgrades configuration, it decided to remove linux- image-generic which also removed linux-modules-extra which caused sound drivers to disappear, etc. The relative snippet from /var/log/unattended-upgrades/unattended- upgrades.log is: 2018-08-15 06:18:00,048 INFO Starting unattended upgrades script 2018-08-15 06:18:00,048 INFO Allowed origins are: o=Ubuntu,a=bionic, o=Ubuntu,a=bionic-security, o=UbuntuESM,a=bionic 2018-08-15 06:18:01,552 INFO Removing unused kernel packages: linux-headers-generic linux-image-generic linux-headers-4.15.0-32-generic linux-headers-4.15.0-32 2018-08-15 06:18:01,588 WARNING Keeping auto-removable linux-headers-generic package(s) because it would also remove the following packages which should be kept in this step: libxml2 linux-image-4.15.0-32-generic linux-modules-4.15.0-32-generic linux-modules-extra-4.15.0-32-generic 2018-08-15 06:18:09,476 INFO Packages that were successfully auto-removed: linux-headers-4.15.0-32 linux-headers-4.15.0-32-generic linux-headers-generic linux-image-generic 2018-08-15 06:18:09,477 INFO Packages that are kept back: linux-headers-generic 2018-08-15 06:18:10,300 INFO Packages that will be upgraded: libxml2 linux-image-generic 2018-08-15 06:18:10,300 INFO Writing dpkg log to /var/log/unattended-upgrades/unattended-upgrades-dpkg.log 2018-08-15 06:18:39,238 INFO All upgrades installed 2018-08-15 06:18:42,818 INFO Packages that were successfully auto-removed: linux-image-generic linux-modules-extra-4.15.0-32-generic 2018-08-15 06:18:42,818 INFO Packages that are kept back: ProblemType: Bug DistroRelease: Ubuntu 18.04 Package: unattended-upgrades 1.1ubuntu1.18.04.5 ProcVersionSignature: Ubuntu 4.15.0-32.35-generic 4.15.18 Uname: Linux 4.15.0-32-generic x86_64 NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair ApportVersion: 2.20.9-0ubuntu7.3 Architecture: amd64 CurrentDesktop: ubuntu:GNOME Date: Thu Aug 16 13:17:30 2018 InstallationDate: Installed on 2018-07-24 (23 days ago) InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180724) PackageArchitecture: all ProcEnviron: TERM=xterm PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_US.UTF-8 SHELL=/bin/bash SourcePackage: unattended-upgrades UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/unattended-upgrades/+bug/1787460/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp