I'm a little confused. You are attempting to update the Ubuntu base that zorin is created on? This makes no sense to me.
Zorin 16 may be based on Ubuntu 20, but does not follow the update schedule of Ubuntu. Zorin is a customized distribution, with the 16.2 update, already surpassing Ubuntu 22. Why would you feel the need to convert zorin to Ubuntu (which is essentially what you're doing), which never goes well.
You don't need to upgrade the distribution of Ubuntu zorin is based... this os already does this by the devs updates.
You can verify what i say by checking and comparing zorin and Ubuntu kernel versions (if that doesn't convince you, verify library and application versions).
This is not a recommended practice. Do a little research and you will find you are using the latest and greatest in comparison to Ubuntu.
Thank you, this clarifies to me what is happening.
I must say that I was using the parents' computer, where I installed Zorin, and it appeared by itself a pop-up window that was suggesting an upgrade to distribution 22.04. I'll screenshot the pop-up window when it appears again.
There are Many Topics on this on the forum:
There currently is no Direct Upgrade Feature on Zorin OS and the popup you got states "Ubuntu."
I can certainly see how this is confusing. However, Zorin OS has that feature turned off by default.
Others, (quite a few) have also noted that they began getting those popups - and they did not go in and change the defaults in the Zorin Files. Many did not even know how to do that.
Since I do know how, it was easy for me to determine that they have been honest about this.
So... Something out there... an application... a script... a customizer program... Something is available out there that changes that default for the user without their knowledge.
I have not yet figured out what it is... many people do not remember what all they installed or tried out or tested over time...
I have confirmed with the ZorinGroup directly, however, that the Ubuntu Dist-Upgrade feature is strictly disabled by default from Zorin - and cannot be mistakenly enabled during Zorin OS .iso download or installation.
I really wish we could narrow down what is out there that is doing this.
It is possible that it it a canonical package that comes through with the other system updates.