Apturl not working out of the box in Firefox on Ubuntu 17.10 Artful

Installed yesterday Ubuntu 17.10 Artful, now up to date.
It seems that AptUrl is not working out-of-the-box in Firefox, even if apturl is pre-installed.

= How to reproduce =
 1. with Firefox, open this wiki page: https://help.ubuntu.com/community/TheGIMP
 2. click on the "gimp" link in the "Standard" chapter, which should start the procedure to install gimp.

Expected: a window opens telling you if you want to install the "gimp" package.
What happen: Firefox tells you that the url can not be interpreted.

Hope you can fix this problem

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: firefox 55.0.2+build1-0ubuntu4
ProcVersionSignature: Ubuntu 4.13.0-12.13-generic 4.13.3
Uname: Linux 4.13.0-12-generic x86_64
NonfreeKernelModules: wl
AddonCompatCheckDisabled: False
ApportVersion: 2.20.7-0ubuntu2
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: alessandro 1219 F.... pulseaudio
BuildID: 20170919185010
Channel: Unavailable
CurrentDesktop: ubuntu:GNOME
Date: Sun Oct 1 16:38:17 2017
Extensions: extensions.sqlite corrupt or missing
ForcedLayersAccel: False
IfupdownConfig:
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback
IncompatibleExtensions: Unavailable (corrupt or non-existant compatibility.ini or extensions.sqlite)
InstallationDate: Installed on 2017-09-30 (0 days ago)
InstallationMedia: Ubuntu 17.10 "Artful Aardvark" - Alpha amd64 (20170926)
IpRoute:
 default via 192.168.1.254 dev wlp9s0 proto static metric 600
 169.254.0.0/16 dev wlp9s0 scope link metric 1000
 192.168.1.0/24 dev wlp9s0 proto kernel scope link src 192.168.1.73 metric 600
Locales: extensions.sqlite corrupt or missing
PrefSources: prefs.js
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=it_IT.UTF-8
 SHELL=/bin/bash
Profiles: Profile0 (Default) - LastVersion=55.0.2/20170919185010 (In use)
RunningIncompatibleAddons: False
SourcePackage: firefox
Themes: extensions.sqlite corrupt or missing
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 03/23/2012
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A04
dmi.board.name: 01HXXJ
dmi.board.vendor: Dell Inc.
dmi.board.version: A04
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.chassis.version: Not Specified
dmi.modalias: dmi:bvnDellInc.:bvrA04:bd03/23/2012:svnDellInc.:pnInspironN5050:pvrNotSpecified:rvnDellInc.:rn01HXXJ:rvrA04:cvnDellInc.:ct8:cvrNotSpecified:
dmi.product.name: Inspiron N5050
dmi.product.version: Not Specified
dmi.sys.vendor: Dell Inc.