Can't install applications: "E: could not get lock /var/lib/dpkg/lock-frontend - open (11: Resource temporarily unavailable)"

[Qasim Ali]

1. Start Software Center.
2. Select an application to install
3. Click install

Expected: application installs
Actual: error message "E: could not get lock /var/lib/dpkg/lock-frontend - open (11: Resource temporarily unavailable)" (see attached screenshot)

Solutions attempted:

1. Closing and re-opening software center
2. Checking 'updates' tab in software center ('Software is up to date')

---

Version information:

$ lsb_release -rd
Description: Ubuntu 18.04.2 LTS
Release: 18.04

$ apt-cache policy gnome-software
gnome-software:
  Installed: 3.28.1-0ubuntu4.18.04.8
  Candidate: 3.28.1-0ubuntu4.18.04.8
  Version table:
 *** 3.28.1-0ubuntu4.18.04.8 500
        500 http://us.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     3.28.1-0ubuntu4 500
        500 http://us.archive.ubuntu.com/ubuntu bionic/main amd64 Packages

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: gnome-software 3.28.1-0ubuntu4.18.04.8
ProcVersionSignature: Ubuntu 4.15.0-45.48-generic 4.15.18
Uname: Linux 4.15.0-45-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Fri Mar 1 20:06:51 2019
InstallationDate: Installed on 2019-01-20 (40 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
InstalledPlugins:
 gnome-software-plugin-flatpak N/A
 gnome-software-plugin-limba N/A
 gnome-software-plugin-snap 3.28.1-0ubuntu4.18.04.8
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-software
UpgradeStatus: No upgrade log present (probably fresh install)

[Sebastien Bacher (seb128)]

Thank you for your bug report, as indicated by the error message (which could probably be a bit nicer/user friendly) the packaging system seems currently locked by another proceess. Did you have any other packaging tools in use at the time? Did that resolve itself after some time?

[Qasim Ali (qasimcanadian)]

Eventually, I got an upgrade notification (it listed a bunch of packages which were scheduled to be updated). I assume whatever process was doing silent updates in the background grabbed the lock, and once I closed the dialog software centre was able to install packages.

Some sort of communication between that background upgrade system and gnome-software would probably help alleviate this sort of confusion.

Thanks,
Qasim

[Sebastien Bacher (seb128)]

Right, it's likely that the system was busy doing a refresh of the indexes or even installing security upgrades in background, those situations are not reflected nicely in the graphical session (and the gnome-software warning is not really nice either)