As of ubuntu 16.04.3, the problem demonstrated below, still exists. Here is the solution as to how to install it on a clean system. Note carefully, I always use apt-get, not synaptic. Also note that the _apt user already exists.
sudo chown _apt /var/lib/update-notifier/package-data-downloads/partial/ sudo apt-get install ttf-mscorefonts-installer First, the Broken before chown to demonstrate the issue: sudo apt-get install ttf-mscorefonts-installer Reading package lists... Done Building dependency tree Reading state information... Done The following additional packages will be installed: cabextract libmspack0 The following NEW packages will be installed: cabextract libmspack0 ttf-mscorefonts-installer 0 upgraded, 3 newly installed, 0 to remove and 0 not upgraded. Need to get 87.9 kB of archives. After this operation, 338 kB of additional disk space will be used. Do you want to continue? [Y/n] Get:1 http://us.archive.ubuntu.com/ubuntu xenial-updates/main amd64 libmspack0 amd64 0.5-1ubuntu0.16.04.1 [37.0 kB] Get:2 http://us.archive.ubuntu.com/ubuntu xenial/universe amd64 cabextract amd64 1.6-1 [21.4 kB] Get:3 http://us.archive.ubuntu.com/ubuntu xenial/multiverse amd64 ttf-mscorefonts-installer all 3.4+nmu1ubuntu2 [29.5 kB] Fetched 87.9 kB in 0s (118 kB/s) Preconfiguring packages ... Selecting previously unselected package libmspack0:amd64. (Reading database ... 241441 files and directories currently installed.) Preparing to unpack .../libmspack0_0.5-1ubuntu0.16.04.1_amd64.deb ... Unpacking libmspack0:amd64 (0.5-1ubuntu0.16.04.1) ... Selecting previously unselected package cabextract. Preparing to unpack .../cabextract_1.6-1_amd64.deb ... Unpacking cabextract (1.6-1) ... Selecting previously unselected package ttf-mscorefonts-installer. Preparing to unpack .../ttf-mscorefonts-installer_3.4+nmu1ubuntu2_all.deb ... Unpacking ttf-mscorefonts-installer (3.4+nmu1ubuntu2) ... Processing triggers for libc-bin (2.23-0ubuntu9) ... Processing triggers for man-db (2.7.5-1) ... Processing triggers for fontconfig (2.11.94-0ubuntu1.1) ... Processing triggers for update-notifier-common (3.168.5) ... ttf-mscorefonts-installer: processing... ttf-mscorefonts-installer: downloading http://downloads.sourceforge.net/corefonts/andale32.exe Get:1 http://downloads.sourceforge.net/corefonts/andale32.exe [198 kB] Fetched 198 kB in 1s (132 kB/s) W: Can't drop privileges for downloading as file '/var/lib/update-notifier/package-data-downloads/partial/andale32.exe' couldn't be accessed by user '_apt'. - pkgAcquire::Run (13: Permission denied) ttf-mscorefonts-installer: downloading http://downloads.sourceforge.net/corefonts/arial32.exe Get:1 http://downloads.sourceforge.net/corefonts/arial32.exe [554 kB] Fetched 554 kB in 1s (364 kB/s) W: Can't drop privileges for downloading as file '/var/lib/update-notifier/package-data-downloads/partial/arial32.exe' couldn't be accessed by user '_apt'. - pkgAcquire::Run (13: Permission denied) ttf-mscorefonts-installer: downloading http://downloads.sourceforge.net/corefonts/arialb32.exe Get:1 http://downloads.sourceforge.net/corefonts/arialb32.exe [168 kB] Fetched 168 kB in 1s (136 kB/s) W: Can't drop privileges for downloading as file '/var/lib/update-notifier/package-data-downloads/partial/arialb32.exe' couldn't be accessed by user '_apt'. - pkgAcquire::Run (13: Permission denied) [..snip..] After purging and then sudo chown _apt /var/lib/update-notifier/package-data-downloads/partial/ We get the fixed: sudo apt-get install ttf-mscorefonts-installerReading package lists... Done Building dependency tree Reading state information... Done The following NEW packages will be installed: ttf-mscorefonts-installer 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. Need to get 0 B/29.5 kB of archives. After this operation, 134 kB of additional disk space will be used. Preconfiguring packages ... Selecting previously unselected package ttf-mscorefonts-installer. (Reading database ... 241463 files and directories currently installed.) Preparing to unpack .../ttf-mscorefonts-installer_3.4+nmu1ubuntu2_all.deb ... Unpacking ttf-mscorefonts-installer (3.4+nmu1ubuntu2) ... Processing triggers for fontconfig (2.11.94-0ubuntu1.1) ... Processing triggers for update-notifier-common (3.168.5) ... ttf-mscorefonts-installer: processing... ttf-mscorefonts-installer: downloading http://downloads.sourceforge.net/corefonts/andale32.exe Get:1 http://downloads.sourceforge.net/corefonts/andale32.exe [198 kB] Fetched 198 kB in 0s (230 kB/s) ttf-mscorefonts-installer: downloading http://downloads.sourceforge.net/corefonts/arial32.exe Get:1 http://downloads.sourceforge.net/corefonts/arial32.exe [554 kB] Fetched 554 kB in 1s (422 kB/s) ttf-mscorefonts-installer: downloading http://downloads.sourceforge.net/corefonts/arialb32.exe Get:1 http://downloads.sourceforge.net/corefonts/arialb32.exe [168 kB] Fetched 168 kB in 0s (207 kB/s) ttf-mscorefonts-installer: downloading http://downloads.sourceforge.net/corefonts/comic32.exe Get:1 http://downloads.sourceforge.net/corefonts/comic32.exe [246 kB] Fetched 246 kB in 1s (208 kB/s) ttf-mscorefonts-installer: downloading http://downloads.sourceforge.net/corefonts/courie32.exe Get:1 http://downloads.sourceforge.net/corefonts/courie32.exe [646 kB] Fetched 646 kB in 2s (281 kB/s) ttf-mscorefonts-installer: downloading http://downloads.sourceforge.net/corefonts/georgi32.exe Get:1 http://downloads.sourceforge.net/corefonts/georgi32.exe [392 kB] Fetched 392 kB in 1s (297 kB/s) ttf-mscorefonts-installer: downloading http://downloads.sourceforge.net/corefonts/impact32.exe Get:1 http://downloads.sourceforge.net/corefonts/impact32.exe [173 kB] Fetched 173 kB in 0s (215 kB/s) ttf-mscorefonts-installer: downloading http://downloads.sourceforge.net/corefonts/times32.exe Get:1 http://downloads.sourceforge.net/corefonts/times32.exe [662 kB] Fetched 662 kB in 1s (625 kB/s) ttf-mscorefonts-installer: downloading http://downloads.sourceforge.net/corefonts/trebuc32.exe Get:1 http://downloads.sourceforge.net/corefonts/trebuc32.exe [357 kB] Fetched 357 kB in 1s (282 kB/s) ttf-mscorefonts-installer: downloading http://downloads.sourceforge.net/corefonts/verdan32.exe Get:1 http://downloads.sourceforge.net/corefonts/verdan32.exe [352 kB] Fetched 352 kB in 0s (397 kB/s) ttf-mscorefonts-installer: downloading http://downloads.sourceforge.net/corefonts/webdin32.exe Get:1 http://downloads.sourceforge.net/corefonts/webdin32.exe [185 kB] Fetched 185 kB in 0s (224 kB/s) These fonts were provided by Microsoft "in the interest of cross- platform compatibility". This is no longer the case, but they are still available from third parties. You are free to download these fonts and use them for your own use, but you may not redistribute them in modified form, including changes to the file name or packaging format. Extracting cabinet: /var/lib/update-notifier/package-data-downloads/partial/andale32.exe extracting fontinst.inf extracting andale.inf extracting fontinst.exe extracting AndaleMo.TTF extracting ADVPACK.DLL extracting W95INF32.DLL extracting W95INF16.DLL All done, no errors. Extracting cabinet: /var/lib/update-notifier/package-data-downloads/partial/arial32.exe extracting FONTINST.EXE extracting fontinst.inf extracting Ariali.TTF extracting Arialbd.TTF extracting Arialbi.TTF extracting Arial.TTF All done, no errors. Extracting cabinet: /var/lib/update-notifier/package-data-downloads/partial/arialb32.exe extracting fontinst.exe extracting fontinst.inf extracting AriBlk.TTF All done, no errors. Extracting cabinet: /var/lib/update-notifier/package-data-downloads/partial/comic32.exe extracting fontinst.inf extracting Comicbd.TTF extracting Comic.TTF extracting fontinst.exe All done, no errors. Extracting cabinet: /var/lib/update-notifier/package-data-downloads/partial/courie32.exe extracting cour.ttf extracting courbd.ttf extracting courbi.ttf extracting fontinst.inf extracting couri.ttf extracting fontinst.exe All done, no errors. Extracting cabinet: /var/lib/update-notifier/package-data-downloads/partial/georgi32.exe extracting fontinst.inf extracting Georgiaz.TTF extracting Georgiab.TTF extracting Georgiai.TTF extracting Georgia.TTF extracting fontinst.exe All done, no errors. Extracting cabinet: /var/lib/update-notifier/package-data-downloads/partial/impact32.exe extracting fontinst.exe extracting Impact.TTF extracting fontinst.inf All done, no errors. Extracting cabinet: /var/lib/update-notifier/package-data-downloads/partial/times32.exe extracting fontinst.inf extracting Times.TTF extracting Timesbd.TTF extracting Timesbi.TTF extracting Timesi.TTF extracting FONTINST.EXE All done, no errors. Extracting cabinet: /var/lib/update-notifier/package-data-downloads/partial/trebuc32.exe extracting FONTINST.EXE extracting trebuc.ttf extracting Trebucbd.ttf extracting trebucbi.ttf extracting trebucit.ttf extracting fontinst.inf All done, no errors. Extracting cabinet: /var/lib/update-notifier/package-data-downloads/partial/verdan32.exe extracting fontinst.exe extracting fontinst.inf extracting Verdanab.TTF extracting Verdanai.TTF extracting Verdanaz.TTF extracting Verdana.TTF All done, no errors. Extracting cabinet: /var/lib/update-notifier/package-data-downloads/partial/webdin32.exe extracting fontinst.exe extracting Webdings.TTF extracting fontinst.inf extracting Licen.TXT All done, no errors. All fonts downloaded and installed. Setting up ttf-mscorefonts-installer (3.4+nmu1ubuntu2) ... -- 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: Warning messages about unsandboxed downloads Status in apt package in Ubuntu: Fix Released Status in aptitude package in Ubuntu: Fix Released Status in synaptic package in Ubuntu: Triaged Status in update-notifier package in Ubuntu: Fix Released Status in apt package in Debian: Fix Released Status in aptitude package in Debian: Fix Released 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
