dbus-daemon[762]: [session uid=999 pid=762] Activating service name='org.gtk.vfs.Daemon' requested by ':1.0' (uid=999 pid=763 comm="" label="unconfined")
dbus-daemon[762]: [session uid=999 pid=762] Successfully activated service 'org.gtk.vfs.Daemon'
dbus-daemon[762]: [session uid=999 pid=762] Activating service name='org.gtk.vfs.Metadata' requested by ':1.0' (uid=999 pid=763 comm="" label="unconfined")
fuse: device not found, try 'modprobe fuse' first
dbus-daemon[762]: [session uid=999 pid=762] Successfully activated service 'org.gtk.vfs.Metadata'

(gvfsd-metadata:774): GUdev-CRITICAL **: 18:15:29.984: g_udev_device_has_property: assertion 'G_UDEV_IS_DEVICE (device)' failed

(gvfsd-metadata:774): GUdev-CRITICAL **: 18:15:29.984: g_udev_device_has_property: assertion 'G_UDEV_IS_DEVICE (device)' failed
A connection to the bus can't be made
Using CD-ROM mount point /cdrom/
Identifying... [ceed225dcf8a8bc50793d6158bd247e0-2]
Scanning disc for index files...
Found 2 package indexes, 0 source indexes, 0 translation indexes and 1 signatures
Found label 'Ubuntu 18.04 LTS _Bionic Beaver_ - Alpha amd64 (20180420)'
This disc is called: 
'Ubuntu 18.04 LTS _Bionic Beaver_ - Alpha amd64 (20180420)'
Copying package lists...gpgv: Signature made Fri Apr 20 07:59:08 2018 UTC
gpgv:                using RSA key D94AA3F0EFE21092
gpgv: Good signature from "Ubuntu CD Image Automatic Signing Key (2012) <cdimage@ubuntu.com>"

Reading Package Indexes... 0%

Reading Package Indexes... Done
Writing new source list
Source list entries for this disc are:
deb cdrom:[Ubuntu 18.04 LTS _Bionic Beaver_ - Alpha amd64 (20180420)]/ bionic main restricted
Repeat this process for the rest of the CDs in your set.