$ sudo appstreamcli refresh --force --verbose
[sudo] password for jhartley: 
** (appstreamcli:3435): DEBUG: Refreshing AppStream cache
** (appstreamcli:3435): DEBUG: Reading: /usr/share/app-info/xmls/org.freedesktop.fwupd.xml
** (appstreamcli:3435): DEBUG: Reading: /var/lib/app-info/yaml/archive.ubuntu.com_ubuntu_dists_xenial_main_dep11_Components-amd64.yml.gz
** (appstreamcli:3435): DEBUG: Reading: /var/lib/app-info/yaml/archive.ubuntu.com_ubuntu_dists_xenial_restricted_dep11_Components-amd64.yml.gz
** (appstreamcli:3435): DEBUG: Reading: /var/lib/app-info/yaml/archive.ubuntu.com_ubuntu_dists_xenial_universe_dep11_Components-amd64.yml.gz
** (appstreamcli:3435): DEBUG: Reading: /var/lib/app-info/yaml/archive.ubuntu.com_ubuntu_dists_xenial_multiverse_dep11_Components-amd64.yml.gz
** (appstreamcli:3435): DEBUG: Reading: /var/lib/app-info/yaml/archive.ubuntu.com_ubuntu_dists_xenial-updates_main_dep11_Components-amd64.yml.gz
** (appstreamcli:3435): DEBUG: Reading: /var/lib/app-info/yaml/archive.ubuntu.com_ubuntu_dists_xenial-updates_restricted_dep11_Components-amd64.yml.gz
** (appstreamcli:3435): DEBUG: Reading: /var/lib/app-info/yaml/archive.ubuntu.com_ubuntu_dists_xenial-updates_universe_dep11_Components-amd64.yml.gz
** (appstreamcli:3435): DEBUG: Reading: /var/lib/app-info/yaml/archive.ubuntu.com_ubuntu_dists_xenial-updates_multiverse_dep11_Components-amd64.yml.gz
** (appstreamcli:3435): DEBUG: Reading: /var/lib/app-info/yaml/archive.ubuntu.com_ubuntu_dists_xenial-security_main_dep11_Components-amd64.yml.gz
** (appstreamcli:3435): DEBUG: Reading: /var/lib/app-info/yaml/archive.ubuntu.com_ubuntu_dists_xenial-security_restricted_dep11_Components-amd64.yml.gz
** (appstreamcli:3435): DEBUG: Reading: /var/lib/app-info/yaml/archive.ubuntu.com_ubuntu_dists_xenial-security_universe_dep11_Components-amd64.yml.gz
** (appstreamcli:3435): DEBUG: Reading: /var/lib/app-info/yaml/archive.ubuntu.com_ubuntu_dists_xenial-security_multiverse_dep11_Components-amd64.yml.gz
** (appstreamcli:3435): DEBUG: Reading: /var/cache/app-info/xmls/fwupd.xml
** (appstreamcli:3435): DEBUG: Detected colliding ids: plan.desktop was already added with the same priority.
** (appstreamcli:3435): DEBUG: Detected colliding ids: flcheckers.desktop was already added with the same priority.
** (appstreamcli:3435): DEBUG: Detected colliding ids: flblocks.desktop was already added with the same priority.
** (appstreamcli:3435): DEBUG: Detected colliding ids: flsudoku.desktop was already added with the same priority.
** (appstreamcli:3435): DEBUG: Replaced 'language-selector.desktop' with data of higher priority.
** (appstreamcli:3435): DEBUG: zathura-pdf-poppler.desktop extends zathura.desktop, but zathura.desktop was not found.
** (appstreamcli:3435): DEBUG: WARNING: Skipped component 'com.steelseries.rival-legacy.firmware': The component is invalid.
** (appstreamcli:3435): DEBUG: Removing old rebuild-dir from previous database rebuild.
AppStream cache update completed, but some metadata was ignored due to errors.
22:14:53:~
$ appstreamcli status
AppStream Status:
Version: 0.9.4

Distribution metadata:
 /usr/share/app-info
  - XML:  1
  - No icons.

 /var/lib/app-info
  - YAML: 12
  - Iconsets:
     ubuntu-xenial-main
     ubuntu-xenial-universe
     ubuntu-xenial-multiverse
     ubuntu-xenial-updates-main

 /var/cache/app-info
  - XML:  1
  - No icons.

Upstream metadata:
  - Found 50 components in legacy paths.

Summary:
The system metadata cache exists.
We have information on 1822 software components.