Public bug reported: the issue is described here: https://wiki.debian.org/Nagios4
in summary, after installing nagios4, apache2 won't restart, until: a2enmod auth_digest a2enmod authz_groupfile ProblemType: Bug DistroRelease: Ubuntu 20.04 Package: nagios4 (not installed) ProcVersionSignature: Ubuntu 5.4.0-42.46-generic 5.4.44 Uname: Linux 5.4.0-42-generic x86_64 ApportVersion: 2.20.11-0ubuntu27.4 Architecture: amd64 CasperMD5CheckResult: pass Date: Thu Apr 29 21:33:16 2021 InstallationDate: Installed on 2020-11-30 (150 days ago) InstallationMedia: Ubuntu-Server 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731) ProcEnviron: TERM=screen PATH=(custom, no user) LANG=C.UTF-8 SHELL=/bin/bash SourcePackage: nagios4 UpgradeStatus: No upgrade log present (probably fresh install) ** Affects: nagios4 (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug focal uec-images -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1926680 Title: apache2 won't restart after installing nagios4 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/nagios4/+bug/1926680/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs