Upgrade problem

[dancingqueen74]

You're welcome - hope that was all understandable.

I don't know of a means to retain the /home partition in Mobian, otherwise I'd recommend reinstalling the rootfs. Unless someone can correct me, I believe the only method of re-installation is via the .img

Thanks
While your comments did not directly lead to a solution, it hinted me into the right direction. I was able to solve this without reinstalling.

What it did was:

root@mobian:/var/lib/apt# grep libgtherm-0.0-0 /var/lib/apt/lists/* | grep "Filename:"
grep: /var/lib/apt/lists/auxfiles: Ist ein Verzeichnis
grep: /var/lib/apt/lists/partial: Ist ein Verzeichnis
/var/lib/apt/lists/deb.debian.org_debian_dists_bullseye_main_binary-arm64_Packages:Filename: pool/main/g/gtherm/libgtherm-0.0-0_0.0.2-1_arm64.deb
/var/lib/apt/lists/repo.mobian-project.org_dists_mobian_main_binary-amd64_Packages:Filename: pool/main/g/gtherm/libgtherm-0.0-0_0.0.2-1_amd64.deb
/var/lib/apt/lists/repo.mobian-project.org_dists_mobian_main_binary-amd64_Packages:Filename: pool/main/g/gtherm/libgtherm-0.0-0-dbgsym_0.0.2-1_amd64.deb
/var/lib/apt/lists/repo.mobian-project.org_dists_mobian_main_binary-arm64_Packages:Filename: pool/main/g/gtherm/libgtherm-0.0-0_0.0.2-1_arm64.deb
/var/lib/apt/lists/repo.mobian-project.org_dists_mobian_main_binary-arm64_Packages:Filename: pool/main/g/gtherm/libgtherm-0.0-0-dbgsym_0.0.2-1_arm64.deb
/var/lib/apt/lists/repo.mobian-project.org_dists_mobian_main_binary-armhf_Packages:Filename: pool/main/g/gtherm/libgtherm-0.0-0_0.0.2-1_armhf.deb
/var/lib/apt/lists/repo.mobian-project.org_dists_mobian_main_binary-armhf_Packages:Filename: pool/main/g/gtherm/libgtherm-0.0-0-dbgsym_0.0.2-1_armhf.deb

I did this for all of the three files, compared it to the same file in the still loop mounted installation image and found that all 3 packages where listed in the according debian.org list, even though all were drawn in from the mobian repo. I deleted all 3 entries from the debian list and run "apt upgrade" and voila: all is fine again