Dear Maintainer,

When downloading a .deb with Firefox, choosing "Open with:
Gnome-software" (approximate translation), gnome-software fails and show
this message (in French) "Impossible d'installer : non pris en charge"
which might be in English "Could not install : not supported".

Journalctl gives a better error:

gnome-software[110920]: failed to convert URL to GsApp: no application
was created for running url-to-app on plugin=appstream with
dedupe-flags=7 with
refine-flags=require-license,require-url,require-size,require-version,require-history,require-setup-action,require-origin,require-related,require-menu-path,require-allow-packages,require-provenance,require-icon,require-permissions,require-origin-hostname,require-runtime,require-screenshots,require-categories,require-project-group,require-developer-name,require-kudos,content-rating
with timeout=60 with search=file:///tmp/mozilla_yvan0/foo.deb, elapsed
time since creation 5ms


However, if I download the file in my home directory and then open it
with gnome-software, it works properly (but unfortunately it does not
log anything in journald to compare).

Maybe it is a bug from Firefox and not gnome-software… Do not hesitate
to ask if you need more information or if you want me to report this
upstream.

Regards,
Yvan