Begin: Running /scripts/casper-premount ... done.
done.
stdin: Invalid argument
stdin: Invalid argument
stdin: Invalid argument
umount: can't umount /cdrom: Device or resource busy
Warning: Unable to find the persistent home medium
stdin: Invalid argument
stdin: Invalid argument
umount: can't umount /cdrom: Device or resource busy
Warning: Impossible to include the casper-sn Snapshot
stdin: Invalid argument
stdin: Invalid argument
umount: can't umount /cdrom: Device or resource busy
Warning: Impossible to include the home-sn Snapshot
done.
Begin: Creating debconf-communicate fifo mechanism ... done.
Begin: Running /scripts/casper-bottom ... Begin: Moving mount points... ... done.
Begin: Configuring fstab... ... done.
Begin: Setting up swap... ... done.
Begin: Setting up locales... ... Generating locales (this might take a while)...
Generation complete.
done.
Begin: Setting up automatic login... ... done.
Begin: Setting hostname... ... done.
Begin: Setting up console keyboard... ... done.
Begin: Applying desktop settings... ... done.
Begin: Regenerating SSL certificate... ... done.
Begin: Preconfiguring networking... ... done.
Begin: Loading preseed file... ... done.
Begin: Adding live session user... ... adduser: The user `ubuntu' already exists.
done.
Begin: Setting up init... ... ln: /root/usr/sbin/anacron: File exists
done.
ln: /root/lib/systemd/system/cdrom.mount: File exists
Begin: Configuring accessibility options... ... done.
Begin: Disabling update-notifier... ... done.
Begin: Configuring power management... ... done.
Begin: Enabling detection of crashes... ... done.
Begin: Disabling unnecessary KDE services... ... done.
Begin: Fixing language selector... ... done.
Begin: Disabling trackerd... ... done.
Begin: Adding APT-CDROM source... ... Using CD-ROM mount point /cdrom/
Identifying... [5aaa6dcd8588aea6732d6cc1864b2936-2]
Scanning disc for index files...
Found 2 package indexes, 0 source indexes, 0 translation indexes and 1 signatures
This disc is called: 
'Ubuntu 16.04 LTS _Xenial Xerus_ - Beta amd64 (20160416)'
Copying package lists...gpgv: Signature made Sat Apr 16 08:02:08 2016 UTC using DSA key ID FBB75451
gpgv: Good signature from "Ubuntu CD Image Automatic Signing Key <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 16.04 LTS _Xenial Xerus_ - Beta amd64 (20160416)]/ xenial main restricted
Repeat this process for the rest of the CDs in your set.
done.
Begin: Possibly disabling update-initramfs (useless on a live CD)... ... done.
Begin: Grant administrative PolicyKit privileges to default user... ... done.
Begin: Configuring jackd2... ... done.
Begin: Disabling unity8's first run wizard... ... done.
done.