Comment 2 for bug 1871615

Per https://launchpadlibrarian.net/473598993/DpkgHistoryLog.txt, unattended-upgrades is running on this system.

Per https://launchpadlibrarian.net/473598999/modified.conffile..etc.apparmor.d.abstractions.base.txt, /etc/apparmor.d/abstraction/base was modified to include:

  # adds networking to all snaps
  network inet,
  network inet6,

Per https://launchpadlibrarian.net/473598994/DpkgTerminalLog.txt, as part of the upgrade, a prompt was presented:

Configuration file '/etc/apparmor.d/abstractions/base'
 ==> Modified (by you or by a script) since installation.
 ==> Package distributor has shipped an updated version.
   What would you like to do about it ? Your options are:
    Y or I : install the package maintainer's version
    N or O : keep your currently-installed version
      D : show the differences between the versions
      Z : start a shell to examine the situation
 The default action is to keep your current version.
*** base (Y/I/N/O/D/Z) [default=N] ? dpkg: error processing package apparmor (--configure):
 end of file on stdin at conffile prompt

but since the upgrade was unattended, the prompt went unanswered.

You should be able to set things right again with: sudo apt-get -f install

This is not a bug in the apparmor package, so marking this task as Invalid.