$ apt upgrade
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Calculating upgrade... Done
Get more security updates through Ubuntu Pro with 'esm-apps' enabled:
  exo-utils libmagick++-6.q16-8 libimage-magick-perl adminer
  libmagickcore-6.q16-6-extra libimage-magick-q16-perl imagemagick
  libmaven3-core-java libgegl-0.4-0 lynx-common python2.7-minimal libhdf5-103
  libmagickwand-6.q16-6 libgegl-common libcgraph6 libpython2.7 python2.7
  libexo-2-0 libolm3 lynx liblab-gamut1 ntpdate imagemagick-6.q16 maven
  libeditorconfig0 libexo-common libopusfile0 libjs-jquery-ui libcdt5
  libpathplan4 libgvpr2 libopenexr24 libmagickcore-6.q16-6
  libpython2.7-minimal libgvc6 libdcmtk14 libpython2.7-stdlib graphviz
  libexo-helpers imagemagick-6-common
Learn more about Ubuntu Pro at https://ubuntu.com/pro
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

# solution
$ rm /etc/apt/apt.conf.d/20apt-esm-hook.conf