December Distro Upgrades and Headaches

This month, I have been trying to fix certain weird issues that ocurred after upgrading Fedora 26 to 26.

The first problem was that, because of space, I had to do a fresh install, so my Mageia GRUB2 was replaced.

Luckily, the problem was not that hard to solve.  Getting my scanner to work was more complicated, but I solved it by getting the iscan bundle from Epson.

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OpenMandriva is giving me headaches with some packages that have an invalid key signature or something... Because of that, LibreOffice is not working properly, I guess..

I reinstalled the distro several times and, when I try to update the packages via OMV control center, the first error message I get reads:
 "Sorry, the following packages cannot be selected:
- gdb-headless-8.0.1-2-omv2015.0.x86_64 (due to unsatisfied urpmi-debuginfo-install)"

I tried to avoid that package and then I get a more worrisome message saying that the package systembase-minimal has an invalid key ID signature.

I have also tried upgrading using the CLI with no luck.

Discover alerts me of 469 packages that must be upgraded.  I will try upgrading from Discover to see what happens this time.

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UPDATE:
Discover installed 177 packages, but stopped. Let's try again with the pending 269...

No luck.  We go back to 469 packages to install.