same cause of this bugs: https://bugs.launchpad.net/ubuntu/+source/update-notifier/+bug/1570141 https://bugs.launchpad.net/ubuntu/+source/pepperflashplugin-nonfree/+bug/1551511 I install a new ppa and run apt-get update and get this error: W: Can't drop privileges for downloading as file '/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_xenial_InRelease' couldn't be accessed by user '_apt'. - pkgAcquire::Run (13: Permissão negada) I am using Ubuntu 16.0 Beta Final, with all the updated packages The permissions: fabio@luzfcb:~$ ls -dl /var/cache/apt/archives/partial/ drwx------ 2 _apt root 4096 Abr 11 21:13 /var/cache/apt/archives/partial/ fabio@luzfcb:~$ ls -dl /var/cache/apt/archives/ drwxr-xr-x 4 root root 28672 Abr 13 19:57 /var/cache/apt/archives/ fabio@luzfcb:~$ grep -B2 _apt /var/lib/dpkg/info/apt.postinst # add unprivileged user for the apt methods adduser --force-badname --system --home /nonexistent \ --no-create-home --quiet _apt || true # Fixup any mistake in the home directory of the _apt user if dpkg --compare-versions "$2" lt-nl 1.1~exp10~; then usermod --home /nonexistent _apt fabio@luzfcb:~$ sudo apt-get update Atingido:1 http://repo.steampowered.com/steam precise InRelease Obter:2 http://archive.ubuntu.com/ubuntu xenial InRelease [247 kB] Ign:3 http://dl.google.com/linux/chrome/deb stable InRelease Atingido:5 http://archive.canonical.com/ubuntu xenial InRelease Atingido:6 http://apt.postgresql.org/pub/repos/apt xenial-pgdg InRelease Atingido:7 http://dl.google.com/linux/chrome/deb stable Release Atingido:9 http://ppa.launchpad.net/gregory-hainaut/pcsx2.official.ppa/ubuntu xenial InRelease Atingido:10 http://ppa.launchpad.net/gwendal-lebihan-dev/hexchat-stable/ubuntu xenial InRelease Atingido:11 http://ppa.launchpad.net/indicator-brightness/ppa/ubuntu xenial InRelease Ign:4 http://toolbelt.heroku.com/ubuntu ./ InRelease Atingido:12 http://ppa.launchpad.net/maarten-baert/simplescreenrecorder/ubuntu xenial InRelease Atingido:14 http://ppa.launchpad.net/saiarcot895/myppa/ubuntu xenial InRelease Obter:15 http://ppa.launchpad.net/webupd8team/java/ubuntu xenial InRelease [17,5 kB] Atingido:13 http://toolbelt.heroku.com/ubuntu ./ Release Obter:17 http://ppa.launchpad.net/webupd8team/java/ubuntu xenial/main amd64 Packages [2.840 B] Atingido:18 http://archive.ubuntu.com/ubuntu xenial-updates InRelease Obter:19 http://ppa.launchpad.net/webupd8team/java/ubuntu xenial/main i386 Packages [2.840 B] Obter:20 http://ppa.launchpad.net/webupd8team/java/ubuntu xenial/main Translation-en [1.260 B] Atingido:21 http://archive.ubuntu.com/ubuntu xenial-backports InRelease Atingido:22 http://archive.ubuntu.com/ubuntu xenial-security InRelease Obter:23 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages [1.184 kB] Obter:24 http://archive.ubuntu.com/ubuntu xenial/main i386 Packages [1.179 kB] Obter:25 http://archive.ubuntu.com/ubuntu xenial/main amd64 DEP-11 Metadata [635 kB] Obter:26 http://archive.ubuntu.com/ubuntu xenial/main DEP-11 64x64 Icons [404 kB] Obter:27 http://archive.ubuntu.com/ubuntu xenial/universe amd64 Packages [7.543 kB] Obter:28 http://archive.ubuntu.com/ubuntu xenial/universe i386 Packages [7.524 kB] Obter:29 http://archive.ubuntu.com/ubuntu xenial/universe Translation-en [4.361 kB] Obter:30 http://archive.ubuntu.com/ubuntu xenial/universe amd64 DEP-11 Metadata [1.846 kB] Obter:31 http://archive.ubuntu.com/ubuntu xenial/universe DEP-11 64x64 Icons [7.482 kB] Baixados 32,4 MB em 2min 19s (233 kB/s) AppStream cache update completed, but some metadata was ignored due to errors. Lendo listas de pacotes... Pronto W: Can't drop privileges for downloading as file '/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_xenial_InRelease' couldn't be accessed by user '_apt'. - pkgAcquire::Run (13: Permissão negada) W: http://dl.google.com/linux/chrome/deb/dists/stable/Release.gpg: Signature by key 4CCA1EAF950CEE4AB83976DCA040830F7FAC5991 uses weak digest algorithm (SHA1) W: http://toolbelt.heroku.com/ubuntu/./Release.gpg: Signature by key 150C6249147592DE6D91981CC927EBE00F1B0520 uses weak digest algorithm (SHA1)