Me too, with this:
OK:1 http://ppa.launchpad.net/nemh/systemback/ubuntu xenial InRelease
OK:2 http://archive.canonical.com xenial InRelease
OK:3 http://ppa.launchpad.net/otto-kesselgulasch/gimp/ubuntu xenial InRelease
OK:4 http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu xenial InRelease
OK:5 http://us.archive.ubuntu.com/ubuntu xenial InRelease
OK:6 http://repo.linuxliteos.com/linuxlite citrine InRelease
Holen:7 http://us.archive.ubuntu.com/ubuntu xenial-security InRelease [102 kB]
Ign:8 http://linux.dropbox.com/ubuntu wily InRelease
Ign:9 http://linux.dropbox.com/ubuntu wily Release
Ign:10 http://linux.dropbox.com/ubuntu wily/main i386 Packages.diff/Index
Ign:11 http://linux.dropbox.com/ubuntu wily/main amd64 Packages.diff/Index
Ign:12 http://linux.dropbox.com/ubuntu wily/main all Packages
Ign:13 http://linux.dropbox.com/ubuntu wily/main Translation-de_DE
Ign:14 http://linux.dropbox.com/ubuntu wily/main Translation-de
Ign:15 http://linux.dropbox.com/ubuntu wily/main Translation-en_US
Ign:16 http://linux.dropbox.com/ubuntu wily/main Translation-en
Ign:17 http://linux.dropbox.com/ubuntu wily/main i386 Packages
Ign:18 http://linux.dropbox.com/ubuntu wily/main amd64 Packages
Holen:19 http://us.archive.ubuntu.com/ubuntu xenial-updates InRelease [102 kB]
Ign:12 http://linux.dropbox.com/ubuntu wily/main all Packages
Ign:13 http://linux.dropbox.com/ubuntu wily/main Translation-de_DE
Ign:14 http://linux.dropbox.com/ubuntu wily/main Translation-de
Ign:15 http://linux.dropbox.com/ubuntu wily/main Translation-en_US
Holen:20 http://us.archive.ubuntu.com/ubuntu xenial-proposed InRelease [253 kB]
Ign:16 http://linux.dropbox.com/ubuntu wily/main Translation-en
Ign:17 http://linux.dropbox.com/ubuntu wily/main i386 Packages
Ign:18 http://linux.dropbox.com/ubuntu wily/main amd64 Packages
Ign:12 http://linux.dropbox.com/ubuntu wily/main all Packages
Ign:13 http://linux.dropbox.com/ubuntu wily/main Translation-de_DE
Ign:14 http://linux.dropbox.com/ubuntu wily/main Translation-de
Holen:21 http://us.archive.ubuntu.com/ubuntu xenial-backports InRelease [102 kB]
Ign:15 http://linux.dropbox.com/ubuntu wily/main Translation-en_US
Holen:22 http://us.archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages [565 kB]
Ign:16 http://linux.dropbox.com/ubuntu wily/main Translation-en
Ign:17 http://linux.dropbox.com/ubuntu wily/main i386 Packages
Ign:18 http://linux.dropbox.com/ubuntu wily/main amd64 Packages
Ign:12 http://linux.dropbox.com/ubuntu wily/main all Packages
Ign:13 http://linux.dropbox.com/ubuntu wily/main Translation-de_DE
Ign:14 http://linux.dropbox.com/ubuntu wily/main Translation-de
Ign:15 http://linux.dropbox.com/ubuntu wily/main Translation-en_US
Ign:16 http://linux.dropbox.com/ubuntu wily/main Translation-en
Ign:17 http://linux.dropbox.com/ubuntu wily/main i386 Packages
Ign:18 http://linux.dropbox.com/ubuntu wily/main amd64 Packages
Ign:12 http://linux.dropbox.com/ubuntu wily/main all Packages
Holen:23 http://us.archive.ubuntu.com/ubuntu xenial-updates/main i386 Packages [547 kB]
Ign:13 http://linux.dropbox.com/ubuntu wily/main Translation-de_DE
Ign:14 http://linux.dropbox.com/ubuntu wily/main Translation-de
Ign:15 http://linux.dropbox.com/ubuntu wily/main Translation-en_US
Ign:16 http://linux.dropbox.com/ubuntu wily/main Translation-en
Ign:17 http://linux.dropbox.com/ubuntu wily/main i386 Packages
Ign:18 http://linux.dropbox.com/ubuntu wily/main amd64 Packages
Ign:12 http://linux.dropbox.com/ubuntu wily/main all Packages
Ign:13 http://linux.dropbox.com/ubuntu wily/main Translation-de_DE
Ign:14 http://linux.dropbox.com/ubuntu wily/main Translation-de
Ign:15 http://linux.dropbox.com/ubuntu wily/main Translation-en_US
Ign:16 http://linux.dropbox.com/ubuntu wily/main Translation-en
Fehl:17 http://linux.dropbox.com/ubuntu wily/main i386 Packages
404 Not Found [IP: 52.222.253.66 80]
Ign:18 http://linux.dropbox.com/ubuntu wily/main amd64 Packages
Holen:24 http://us.archive.ubuntu.com/ubuntu xenial-updates/universe amd64 Packages [488 kB]
Holen:25 http://us.archive.ubuntu.com/ubuntu xenial-updates/universe i386 Packages [470 kB]
Holen:26 http://us.archive.ubuntu.com/ubuntu xenial-proposed/main amd64 Packages [117 kB]
Holen:27 http://us.archive.ubuntu.com/ubuntu xenial-proposed/main Translation-en [45,9 kB]
Holen:28 http://us.archive.ubuntu.com/ubuntu xenial-proposed/universe amd64 Packages [53,1 kB]
Holen:29 http://us.archive.ubuntu.com/ubuntu xenial-proposed/universe Translation-en [19,9 kB]
Es wurden 2.866 kB in 6 s geholt (444 kB/s).
Paketlisten werden gelesen...
W: The repository 'http://linux.dropbox.com/ubuntu wily Release' does not have a Release file.
E: Fehlschlag beim Holen von http://linux.dropbox.com/ubuntu/dists/wily/main/binary-i386/Packages 404 Not Found [IP: 52.222.253.66 80]
E: Einige Indexdateien konnten nicht heruntergeladen werden. Sie wurden ignoriert oder alte an ihrer Stelle benutzt.
I've deactivated Dropbox ppa and now Lite Update was finished with success.