running apt-clone backup on a restored system results in many file not found errors

[rolandu]

apt-clone is part of my normal daily backup routine. Recently my system broke and I restored it using apt-clone. Worked great.

The problem is, now the backup routine (on the restored system) does not work well anymore. During repack it packs dozens of packages and fails during that process, which it did not do before.

The system is Debian 10.6 stable and I restored from-to identical distro versions.

Running backup now, I get lots of errors like this:

dpkg-deb: building package 'firefox-esr' in './firefox-esr_68.2.0esr-1~deb10u1_amd64.deb'.
dpkg-repack: Problems were encountered in processing.
dpkg-repack: The package may be broken.
dpkg-repack: File not found: /usr/lib/x86_64-linux-gnu/libavcodec.so.57.64.101
dpkg-repack: File not found: /usr/share/doc/libavcodec57
dpkg-repack: File not found: /usr/share/doc/libavcodec57/changelog.Debian.gz

and this is the end of the log:

not installable: gcc-6, libva-x11-1, php7.0-json, openjdk-8-jre, php7.0-zip, libisl15, gcc-6-base, libprocps6, libsndio6.1, libwebpmux2, php7.0-common, libgnome-keyring-common, libvpx4, libunistring0, cpp-6, libswresample2, openjdk-8-jre-headless, php7.0-mbstring, php7.0-readline, libx265-95, libdns-export162, libasan3, libgnome-keyring0, libicu57, libmpfr4, libva-drm1, libx264-148, php7.0-intl, perl-modules-5.24, libgcc-6-dev, php7.0-xml, php7.0-cli, php7.0-bz2, libavutil55, libcryptsetup4, liblogging-stdlog0, php7.0, libisc-export160, libapache2-mod-php7.0, gir1.2-gnomekeyring-1.0, libssl1.0.2, php7.0-gd, php7.0-opcache, libva1, libgdbm3, firefox-esr, libavcodec57
version mismatch: phpmyadmin

At least some of these packages are old. gcc-6 was in Debian oldstable, but not in stable anymore. Therefore, I believe that I had it on my old system and it was part of the package list, but during restore it could not be installed (because it is not in the Debian stable repo). Still, apt-clone is looking for it now, and it is not there.

apt install gcc-6 does not work, the package does not exist, but I can remove it.

Any idea how I can solve this? Maybe I should just remove all of these packages? (which do not seem to be installed anyway)

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This is the command I use to backup:

sudo apt-clone clone --with-dpkg-repack /somewhere

This is the command I used to restore:

apt-clone restore apt-clone-state-[HOSTNAME].tar.gz