Hello Ladies and Gentlemen!
I've read in the new Zorin Blog Article that the Upgrade Option is now for Testing Purposes available:
So, if You want try it feel free to do. But of Course be careful and prepare with a BackUp of Your Data and a ready-to-use Zorin Installation Stick for worst Case. Before the Upgrade, I would suggest to at least disable all third-Party Repo's or better delete them and add them after the Upgrade for the new Base.
I decided in 2021, I was no longer going to be a BETA tester for anyone or anything. I value my time, and the condition of my PC. When I use the upgrade, it will be such time, that the upgrade process is no longer in BETA, and OS 18 has had the initial bugs reported, fixed.
You wanna hear some funny timing? I was just thinking as I read your post, thats funny, why haven't I gotten an email then about the upgrade? Then just as I was typing this post, I got a notification about the upgrade in my email lol. 
Ran it this morning and it errored out... report sent. rebooted and 17 came up without problems.
It's bricked my computer today going 17 Pro to 18 Pro. First 2 attempts, it gave an Oops Something went wrong message. Later attempts, it got past this, then got stuck at a screen with Thunderbird, Deja Dup and Rambox
Do you have any third-Party Repo's added? If yes, remove them and try it again.
Did you had these Programs open? If yes, close them and other open Programs and then try it again.
hi @Ponce-De-Leon.
I don't know what 3rd party repos are, but I can't do anything about them and open programmes, as I can't get into Zorin at all and the mouse has no effect on these open apps - it did help me close some of the open apps, but not these. These, I think, are startup apps. But all I can do is turn off the computer using the Power button.
Reinstall Zorin 17 Pro from Ventoy, then try to run Time shift and Deja Dup - yes?
I'm testing on a VM. The upgrade didn't work for me, but no harm done:
[CHECKING:Calculating Upgradeable Packages]
Fatal Error: { GDBus.Error:org.aptkit.TransactionFailed: error-dep-resolution-failed:
E:Internal Error, pkgProblemResolver::ResolveByKeep is looping on package libsane1:amd64. }
Upgrading from 17 to 18 and when finished instructed to reboot. That is when I received this error: "Oh No! Something has gone wrong.A problem has occurred and the system can't recover......"
Options?
Thanks
Does it power up to the login screen ok? I suggest you open a new thread to get help with this specific issue. Our goal should be to get you to the terminal whereupon you can Timeshift back to a working system. I don't think you should re-install Zorin at this stage.
EDIT: Also, because you bought Pro, you do get official support to help you install it. Check the email you got when you purchased it.
Yeah, they do warn not to do testing on a production machine in the email. VMs are good for this 
When does that message appear? After login? At the login screen? Before the login screen? Other?
EDIT: This thread may help too:
Thanks. Just comes up to the error window. This is one of old backup computers. Surface Pro 4 from 2017! I'll check the email,thanks.
Check out the link i just posted (edited my post) - someone appeared to have had the same issue, and they overcame it.
Update worked via sudo apt upgrade ... Im checking my apps now but so far so good!
I love that title oh no, something went wrong. The answer as to why so cryptic, it reminds me of a story point in Alien Isolation.
Time index 12:38
You need to do it in the correct order. Oh no, is Apollo owned by Microsoft?
@d-man It never shows the login screen.
I put it here to share my experience of the update. I have added it to another thread started by someone else who had the same problem. I HAVE contacted Support and am waiting.
@humeston I have the same. After 3 attempts, it went past that screen, but stuck on opening startup apps, even though I'd not even logged in,
Oh awesome. I managed to start the upgrade. Aaaaannndddd i got the same problem!
But! I don't know how to get to Grub in a VM (normally the system just boots, no Grub selections). ESC doesn't seem to do anything 
Anyone know how to force a grub menu in a VM?
EDIT: I was able to tell it to go to the tty with ctrl+alt+f2 (using the menu, not with the keyboard which does it on the host machine rather than the guest VM).
EDIT2: The dist-upgrade step is significant, it took ages. It seems strange that it wouldn't be pre-reboot, or didn't properly complete pre-reboot. It included some user interaction. I don't remember the first, but the second was geoclue update.
After the reboot, it worked fine.
Thanks @xtoph, who provided the instructions (linked earlier but here for ease of reference):
apt update && apt dist-upgrade
apt clean
apt autoremove
reboot
With that, i mean if You have added Sources for downloading Programs. A simple Example: Zorin includes by default the Brave Repo to offer Brave as .deb Version.
Resolved. Got the Oh Oh message upgrading to 18 from 17 so just downloaded 18 and did the full install manually. Everything looks OK except my touch screen doesn't work. Running it on Microsoft Surface Pro 4 which I bought in 2017.
Would love to know how to get the touch screen working if anyone knows.