I modified /etc/apt/apt.conf.d/50appstream so it'd log to a file and provide more details e.g.
# Refresh AppStream cache when APT's cache is updated (i.e. apt update) APT::Update::Post-Invoke-Success { "if /usr/bin/test -w /var/cache/app-info -a -e /usr/bin/appstreamcli; then appstreamcli refresh-cache --verbose > /tmp/appstream-cli.log; fi"; }; Attached is the appstream-cli.log file. ** Attachment added: "appstream-cli.log" https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1790693/+attachment/5184591/+files/appstream-cli.log ** Also affects: appstream (Ubuntu) Importance: Undecided Status: New ** Changed in: appstream (Ubuntu) Importance: Undecided => High ** Tags added: rls-cc-incoming -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to appstream in Ubuntu. https://bugs.launchpad.net/bugs/1790693 Title: appstreamcli crash when attempting release upgrade to cosmic Status in appstream package in Ubuntu: New Status in ubuntu-release-upgrader package in Ubuntu: New Bug description: (appstreamcli:7417): GLib-^[[1;35mCRITICAL^[[0m **: ^[[34m10:34:15.801^[[0m: g_variant_builder_end: assertion '!GVSB(builder)->uniform_item_types || GVSB(builder)->prev_item_type != NULL || g_variant_type_is_definite (GVSB(builder)->type)' failed^M ^M (appstreamcli:7417): GLib-^[[1;35mCRITICAL^[[0m **: ^[[34m10:34:15.802^[[0m: g_variant_new_variant: assertion 'value != NULL' failed^M ^M (appstreamcli:7417): GLib-^[[1;31mERROR^[[0m **: ^[[34m10:34:15.802^[[0m: g_variant_new_parsed: 11-13:invalid GVariant format string^M Trace/breakpoint trap (core dumped)^M ProblemType: Bug DistroRelease: Ubuntu 18.04 Package: ubuntu-release-upgrader-core 1:18.04.22 ProcVersionSignature: User Name 4.15.0-30.32-generic 4.15.18 Uname: Linux 4.15.0-30-generic x86_64 ApportVersion: 2.20.9-0ubuntu7.2 Architecture: amd64 CrashDB: ubuntu CurrentDesktop: ubuntu:GNOME Date: Tue Sep 4 10:39:20 2018 InstallationDate: Installed on 2018-08-13 (21 days ago) InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426) PackageArchitecture: all ProcEnviron: TERM=xterm-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_US.UTF-8 SHELL=/bin/bash SourcePackage: ubuntu-release-upgrader Symptom: ubuntu-release-upgrader UpgradeStatus: Upgraded to bionic on 2018-09-04 (0 days ago) VarLogDistupgradeAptlog: Log time: 2018-09-04 10:29:56.386079 Log time: 2018-09-04 10:29:59.174856 Log time: 2018-09-04 10:34:17.437696 modified.conffile..etc.update-manager.release-upgrades: [modified] mtime.conffile..etc.update-manager.release-upgrades: 2018-09-04T09:43:22.733910 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/appstream/+bug/1790693/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp