Check to see if you have an _apt user: cat /etc/passwd | grep apt
_apt:x:105:65534::/nonexistent:/bin/false If you do, no need to add the user. Otherwise, adduser --force-badname --system --home /nonexistent --no-create-home --quiet _apt || true I haven't verified that it creates precisely the user necessary. If I remember correctly, /bin/false means no shell access so make sure the user created does in fact have /bin/false in passwd. Also it has no group (65534). That is it really. Finally check the directory situation: ls -la /var/lib/update-notifier/package-data-downloads/ drwxr-xr-x 2 _apt root 4096 Nov 9 10:23 partial As you can see "_apt" is properly listed as the owner. If not, sudo chown _apt /var/lib/update-notifier/package-data-downloads/partial/ My system already had an _apt user, but did not have proper directory permissions. At least, I have to assume that this is a proper fix. If not, somebody more knowledgeable should be speaking up and sorting this out... -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to apt in Ubuntu. https://bugs.launchpad.net/bugs/1522675 Title: Can't drop privileges for downloading : _apt user not allowed Status in apt package in Ubuntu: Confirmed Status in dpkg package in Ubuntu: Confirmed Status in synaptic package in Debian: New Bug description: Recently we got new versions for synaptic 0.82+build1 & apt 1.1.3, but now get that error when installing/upgrading some packages: Setting up libc6-dbg:amd64 (2.21-0ubuntu5) ... Processing triggers for libc-bin (2.21-0ubuntu5) ... W: Can't drop privileges for downloading as file '/root/.synaptic/tmp//tmp_cl' couldn't be accessed by user '_apt'. - pkgAcquire::Run (13: Permission denied) From nautilus, i'm seeing a /root/ folder locked (x on its icon) and the folder is empty (no /.synaptic/ sub-folder or file), so the above error. oem@u64:~$ ls -l .synaptic total 4 -rw-rw-r-- 1 oem oem 0 Aug 25 11:19 options -rw-rw-r-- 1 oem oem 236 Aug 25 11:19 synaptic.conf oem@u64:~$ ls -l /var/lib/apt/lists/ .... -rw-r----- 1 root root 0 Sep 20 06:36 lock drwx------ 2 _apt root 16384 Sep 24 15:25 partial ...... oem@u64:~$ sudo ls -l /var/lib/update-notifier/package-data-downloads/ ..... drwxr-xr-x 2 _apt root 4096 Sep 22 23:33 partial ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: synaptic 0.82+build1 ProcVersionSignature: Ubuntu 4.3.0-1.10-generic 4.3.0 Uname: Linux 4.3.0-1-generic x86_64 NonfreeKernelModules: nvidia ApportVersion: 2.19.2-0ubuntu8 Architecture: amd64 CurrentDesktop: GNOME Date: Fri Dec 4 05:23:25 2015 SourcePackage: synaptic UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/apt/+bug/1522675/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp