Reading state information... Done
You might want to run 'apt --fix-broken install' to correct these.
The following packages have unmet dependencies:
 libc-bin : Depends: libc6 (< 2.25) but 2.27-3 is to be installed
 locales : Depends: libc-bin (> 2.27) but 2.24-11+deb9u3 is to be installed
E: Unmet dependencies. Try 'apt --fix-broken install' with no packages (or specify a solution).

The following packages were automatically installed and are no longer required:
  bc cups-browsed cups-core-drivers cups-daemon cups-filters cups-filters-core-drivers
  cups-ppdc cups-server-common dc foomatic-db-compressed-ppds foomatic-db-engine hp-ppd
  hplip-data libart-2.0-2 libavahi-glib1 libcupscgi1 libcupsmime1 libcupsppdc1
  libfontembed1 libgutenprint2 libhpmud0 liblouisutdml-bin liblouisutdml-data
  liblouisutdml7 libqpdf17 libsane-hpaio libsnmp-base libsnmp30 mscompress
  openprinting-ppds printer-driver-all printer-driver-brlaser printer-driver-c2050
  printer-driver-c2esp printer-driver-cjet printer-driver-dymo printer-driver-escpr
  printer-driver-foo2zjs printer-driver-foo2zjs-common printer-driver-fujixerox
  printer-driver-hpijs printer-driver-m2300w printer-driver-min12xxw
  printer-driver-pnm2ppa printer-driver-ptouch printer-driver-pxljr
  printer-driver-sag-gdi python3-pexpect python3-pil python3-ptyprocess
  python3-renderpm python3-reportlab python3-reportlab-accel qpdf ssl-cert
Use 'sudo apt autoremove' to remove them.
The following packages will be REMOVED:
  cups hplip libc-bin locales printer-driver-gutenprint printer-driver-hpcups
  printer-driver-postscript-hp printer-driver-splix task-english task-print-server
WARNING: The following essential packages will be removed.
This should NOT be done unless you know exactly what you are doing!
  libc-bin
0 upgraded, 0 newly installed, 10 to remove and 7 not upgraded.
1 not fully installed or removed.
After this operation, 22.0 MB disk space will be freed.
You are about to do something potentially harmful.
To continue type in the phrase 'Yes, do as I say!'
 ?]

$ cat /etc/apt/sources.list
# deb cdrom:[Debian GNU/Linux 9.4.0 _Stretch_ - Official amd64 NETINST 20180310-11:21]/ stretch main
# deb cdrom:[Debian GNU/Linux 9.4.0 _Stretch_ - Official amd64 NETINST 20180310-11:21]/ stretch main
deb http://ftp.de.debian.org/debian/ stretch main non-free contrib
deb-src http://ftp.de.debian.org/debian/ stretch main non-free contrib

deb http://security.debian.org/debian-security stretch/updates main contrib non-free
deb-src http://security.debian.org/debian-security stretch/updates main contrib non-free

# stretch-updates, previously known as 'volatile'
deb http://ftp.de.debian.org/debian/ stretch-updates main contrib non-free
deb-src http://ftp.de.debian.org/debian/ stretch-updates main contrib non-free