Comment 3 for bug 1551511

i have the same error message: "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 think this error may be the apt-get and not pepperflashplugin-nonfree

full traceback:

fabio@luzfcb:~$ sudo apt-get update
[sudo] senha para fabio:
Obter:1 http://repo.steampowered.com/steam precise InRelease [2.842 B]
Obter:2 http://archive.ubuntu.com/ubuntu xenial InRelease [247 kB]
Ign:3 http://dl.google.com/linux/chrome/deb stable InRelease
Atingido:4 http://ppa.launchpad.net/gregory-hainaut/pcsx2.official.ppa/ubuntu xenial InRelease
Atingido:5 http://archive.canonical.com/ubuntu xenial InRelease
Atingido:6 http://dl.google.com/linux/chrome/deb stable Release
Atingido:7 http://ppa.launchpad.net/gwendal-lebihan-dev/hexchat-stable/ubuntu xenial InRelease
Obter:8 http://dl.google.com/linux/chrome/deb stable Release.gpg [181 B]
Obter:9 http://repo.steampowered.com/steam precise/steam Sources [550 B]
Atingido:10 http://apt.postgresql.org/pub/repos/apt xenial-pgdg InRelease
Atingido:11 http://ppa.launchpad.net/indicator-brightness/ppa/ubuntu xenial InRelease
Atingido:12 http://ppa.launchpad.net/maarten-baert/simplescreenrecorder/ubuntu xenial InRelease
Atingido:13 http://archive.ubuntu.com/ubuntu xenial-updates InRelease
Obter:14 http://repo.steampowered.com/steam precise/steam amd64 Packages [606 B]
Atingido:15 http://archive.ubuntu.com/ubuntu xenial-backports InRelease
Atingido:16 http://ppa.launchpad.net/saiarcot895/myppa/ubuntu xenial InRelease
Atingido:17 http://archive.ubuntu.com/ubuntu xenial-security InRelease
Obter:18 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages [1.197 kB]
Obter:19 http://repo.steampowered.com/steam precise/steam i386 Packages [803 B]
Obter:20 http://archive.ubuntu.com/ubuntu xenial/main i386 Packages [1.193 kB]
Obter:21 http://archive.ubuntu.com/ubuntu xenial/main Translation-en [567 kB]
Obter:22 http://archive.ubuntu.com/ubuntu xenial/main amd64 DEP-11 Metadata [636 kB]
Obter:23 http://archive.ubuntu.com/ubuntu xenial/main DEP-11 64x64 Icons [400 kB]
Obter:24 http://archive.ubuntu.com/ubuntu xenial/universe amd64 Packages [7.479 kB]
Obter:25 http://archive.ubuntu.com/ubuntu xenial/universe i386 Packages [7.460 kB]
Obter:26 http://archive.ubuntu.com/ubuntu xenial/universe Translation-en [4.350 kB]
Obter:27 http://archive.ubuntu.com/ubuntu xenial/universe amd64 DEP-11 Metadata [1.849 kB]
Obter:28 http://archive.ubuntu.com/ubuntu xenial/universe DEP-11 64x64 Icons [7.484 kB]
Obter:29 http://archive.ubuntu.com/ubuntu xenial/multiverse amd64 Packages [146 kB]
Obter:30 http://archive.ubuntu.com/ubuntu xenial/multiverse i386 Packages [142 kB]
Baixados 33,2 MB em 1min 11s (465 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)