all you have to do is go to
/var/lib/dpkg/status
scroll thru to you hit the package base-files, which looks like
Package: base-files
Essential: yes
Status: install ok installed
Priority: required
Section: admin
Installed-Size: 350
Maintainer: Santiago Vila <sanvila@debian.org>
Architecture: amd64
Multi-Arch: foreign
Version: 13.5
Replaces: base, dpkg (<= 1.15.0), miscutils
Provides: base, usr-is-merged
Pre-Depends: awk
Breaks: debian-security-support (<< 2019.04.25), initscripts (<< 2.88dsf-13.3), sendfile (<< 2.1b.20080616-5.2~)
Conffiles:
/etc/debian_version 418bf63c34339f803ffaab19df71f611
/etc/dpkg/origins/debian c47b6815f67ad1aeccb0d4529bd0b990
/etc/host.conf 4eb63731c9f5e30903ac4fc07a7fe3d6
/etc/issue 4fa62803f216112e94adefbaafed16ab
/etc/issue.net 06ea14875beb99190dfc548d4ecd24de
/etc/update-motd.d/10-uname 9e1b832b7b06f566156e7c9e0548247b
Description: Debian base system miscellaneous files
This package contains the basic filesystem hierarchy of a Debian system, and
several important miscellaneous files, such as /etc/debian_version,
/etc/host.conf, /etc/issue, /etc/motd, /etc/profile, and others,
and the text of several common licenses in use on Debian systems.
apt policy base-files
make sure apt policy matches what status says
if they don't match, change it in status, reboot, apt update; apt full-upgrade and no more errors
i don't use debian anymore