nginx error while upgrading raspi

Question

When I try to upgrade my raspi I get an error message:

seb@raspi:~ $ sudo apt-get upgrade
Paketlisten werden gelesen... Fertig
Abhängigkeitsbaum wird aufgebaut.
Statusinformationen werden eingelesen.... Fertig
Paketaktualisierung (Upgrade) wird berechnet... Fertig
Die folgenden Pakete wurden automatisch installiert und werden nicht mehr benötigt:
  realpath squeak-plugins-scratch squeak-vm
Verwenden Sie »sudo apt autoremove«, um sie zu entfernen.
0 aktualisiert, 0 neu installiert, 0 zu entfernen und 0 nicht aktualisiert.
2 nicht vollständig installiert oder entfernt.
Nach dieser Operation werden 0 B Plattenplatz zusätzlich benutzt.
Möchten Sie fortfahren? [J/n] j
nginx-extras (1.10.3-1+deb9u1) wird eingerichtet ...
Job for nginx.service failed because the control process exited with error code.
See "systemctl status nginx.service" and "journalctl -xe" for details.
invoke-rc.d: initscript nginx, action "start" failed.
● nginx.service - A high performance web server and a reverse proxy server
   Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled)
   Active: failed (Result: exit-code) since Fri 2018-08-10 11:16:44 CEST; 65ms ago
     Docs: man:nginx(8)
  Process: 2831 ExecStart=/usr/sbin/nginx -g daemon on; master_process on; (code=exited, status=1/FAILURE)
  Process: 2828 ExecStartPre=/usr/sbin/nginx -t -q -g daemon on; master_process on; (code=exited, status=0/SUCCESS)

Aug 10 11:16:42 raspi nginx[2831]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Aug 10 11:16:43 raspi nginx[2831]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Aug 10 11:16:43 raspi nginx[2831]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Aug 10 11:16:43 raspi nginx[2831]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Aug 10 11:16:43 raspi nginx[2831]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Aug 10 11:16:44 raspi nginx[2831]: nginx: [emerg] still could not bind()
Aug 10 11:16:44 raspi systemd[1]: nginx.service: Control process exited, code=exited status=1
Aug 10 11:16:44 raspi systemd[1]: Failed to start A high performance web server and a reverse proxy server.
Aug 10 11:16:44 raspi systemd[1]: nginx.service: Unit entered failed state.
Aug 10 11:16:44 raspi systemd[1]: nginx.service: Failed with result 'exit-code'.
dpkg: Fehler beim Bearbeiten des Paketes nginx-extras (--configure):
 Unterprozess installiertes post-installation-Skript gab den Fehlerwert 1 zurück
dpkg: Abhängigkeitsprobleme verhindern Konfiguration von nginx:
 nginx hängt ab von nginx-full (<< 1.10.3-1+deb9u1.1~) | nginx-light (<< 1.10.3-1+deb9u1.1~) | nginx-extras (<< 1.10.3-1+deb9u1.1~); aber:
  Paket nginx-full ist nicht installiert.
  Paket nginx-light ist nicht installiert.
  Paket nginx-extras ist noch nicht konfiguriert.
 nginx hängt ab von nginx-full (>= 1.10.3-1+deb9u1) | nginx-light (>= 1.10.3-1+deb9u1) | nginx-extras (>= 1.10.3-1+deb9u1); aber:
  Paket nginx-full ist nicht installiert.
  Paket nginx-light ist nicht installiert.
  Paket nginx-extras ist noch nicht konfiguriert.

dpkg: Fehler beim Bearbeiten des Paketes nginx (--configure):
 Abhängigkeitsprobleme - verbleibt unkonfiguriert
Fehler traten auf beim Bearbeiten von:
 nginx-extras
 nginx
E: Sub-process /usr/bin/dpkg returned an error code (1)
seb@raspi:~ $

Unfortunately I have no idea how to handle this and where this belongs to. The things I set up seem to be working just fine. I don't know where nginx is coming from. I use the raspi mainly as pi hole and have ssh/vnc enabled and an connected an external hdd which I use as home network internal git server and backup drive through a samba server.

I see that the problem is that it wants to bind a port that is already in use but I don't know by whom or for what I would even need nginx or how to configure it.

Answer 1

nginx is missing some packets it depends on. Your error message says (translated):

dpkg: dependencies prevent configuration of nginx:
 nginx depends on nginx-full (<< 1.10.3-1+deb9u1.1~) | nginx-light (<< 1.10.3-1+deb9u1.1~) | nginx-extras (<< 1.10.3-1+deb9u1.1~); but:
  packet nginx-full not installed.
  packet nginx-light not installed.
  packet nginx-extras not yet configured.

Try to reinstall it with this commands in the hope it will also install the missing packets.

rpi ~$ sudo apt update
rpi ~$ sudo apt install --reinstall --install-recommends nginx
rpi ~$ sudo apt full-upgrade

Reboot.

It is also a good idea to follow the suggestion from the message you have quoted:

The following packets are installed automatically but no longer needed:
  realpath squeak-plugins-scratch squeak-vm
Use »sudo apt autoremove«, to remove them.