sudo apt update && sudo apt install --reinstall zorin-os-desktop
@Aravisian seems the broken packages are holding back the sought after corrections.
If I wasn't using the Software Store, Software and Updates nor the Software Updater, I don't know if I could tell anything was awry. (I have the popOS store now.) But I suspect the chasm will only get wider over time.
You said when this happened to you earlier, it took a lot of time and effort. I don't think I have the understanding yet to do all that may be required. And I don't want to impose on you for all the help it sounds like this could ultimately require.
I have two more questions I will humbly ask, if you don't mind, and then if they have no merit, I think I will go the reinstall route. One difference between your experience with doing upgrades over temporary repositories and mine is that you forgot to remove the repositories. In my case, I didn't know I needed to. So this is at least one more thing I am learning about Linux in this scenario.
My questions is related to the files I should remove from /etc/apt/sources.list/.d. First, the files I removed were not explicitly labeled as popOS repositories to my newbie eyes. The files were named approximately "popOS-stable-focal.list" and "popOS-stable-focal.list.save". Do these look like the repository files you were asking me to remove?
Everything else in this folder has ZorinOS in its name except for the following two files: "xubuntu-dev-ubuntu-staging-focal.list" and "xubuntu-dev-ubuntu-staging-focal.list.save". Should I try removing these two files, too?
Correct me if I am wrong, but if my memory serves me correct, doesn't installation of Popsicle add PopOS repositories. Think we put out a public health warning when we had similar issues before, to remove Pop repositories after Popsicle is installed to avoid Pop updating and messing Zorin.
Anyone else remember this?
Ah, if this is true, that explains the PopOS repositories. I just assumed it was something I had done. But earlier when I was giving PopOS a spin, I didn't actually install it. But yes, I did install Popsicle about a month ago and I did miss the public health warning. But lesson still learned about one more thing to consider when installing software.
Would removing Popsicle help at this point?
Yes.
The repository I had added but forgot to remove was for Linux Mint. Mint does something strange with the mintsources - which must be uninstalled rather than just removed.
That made things more complicated.
At the time, I traced my "fixing" steps and outlined them in a text file in my Documents folder in case anyone on the forum runs into the same issue.
You can choose whether you want to or not on these. They have no effect on the packages in question.
Yes, I suspected from the outset that this is how the Pop_OS repo was added in the first place.
No, because it is only one package that deals only with itself, not with the desktop.
The Public Health Warning on Other Distro Repositories would amount to:
This Problem can arise if a Distro is using a Higher Version of Gnome Or other essential packages and their repository is added to Zorin OS to get a specific single package; If the Updater is run, it will upgrade all packages available in the repository.
Thank you, Aravisian and zabadabadoo. A nugget at a time, I am learning more about Linux. Linux is also helping me practice patience and perseverance. Not sure I will have any time to do the reinstall yet this weekend. Probably next weekend.
Actually a question about the reinstall. Would it be better to burn a new iso so I have the current one from Zorin or can I use the iso I burned when Z16 Pro was first released and then do update/upgrade commands after install?
Again, thank you for all you do here on the forum.
Either should work out fine.
Thanks!!!
Pop! OS is a nice upgrade 
I think I used a flatpak or similar install from the store. Maybe. My memory is pretty vague at this point. In any event I missed the Public Health Warning. My bad.
It might be better served more prominently displayed than as a regular post buried in a thread...
For some reason, other's have had to add the repo in order to install Popsicle. I never had to however, I just went into the software store, typed Popsicle, found it, installed it. I think its installed as a SNAP or FLATPAK IDK.
But yes, anytime you add a POP OS repo, your probably doing it so you can install some APP. If you don't remove the repo before updating the system, you can cause all sorts of system wide issues. Easy and quicker way to remove a repo, is to go to your software and updates app, then go to the OTHER SOFTWARE tab, and delete the POP OS repo there.
Sometimes when you have a 3rd party repo that is no longer valid, the system will force you to remove said repo to update the system in general too.
Done:
Hi again,
I am in the middle of reinstalling ZorinOS 16 Pro from the ISO file I originally used back in August. Post install, to upgrade will these be sufficient:
sudo apt update
sudo apt upgrade
Or is their a command needed that is something like
sudo apt dist upgrade
I at least read something like this somewhere. Maybe it’s needed when the district has upgraded to a new kernel which I believe Zorin has done since the August release.
sudo apt update && sudo apt upgrade should be sufficient. I have never had to use dist-upgrade.
PS - Thanks for marking the solution but I believe Partial Upgrade through Software Updater? - #2 by StarTreker was the correct response to your OP that started this thread, so I changed the solution to that. If you disagree, please feel free to correct but as I understand, my response here was to your follow-up question and not a response to your OP, hence I didn't think it warranted being marked as the solution.