A few users have run into an issue where not all sources are updated in their sources to the correct repository after running the Zorin Upgrader.
I would like to post a means of quickly addressing this for users.
Perform these steps after you have run the Zorin Upgrader and rebooted.
First, create backups of your essential files:
sudo cp /etc/apt/sources.list /etc/apt/sources.list.backup
sudo cp -r /etc/apt/sources.list.d /etc/apt/sources.list.d.backup
Certain Manually installed repositories like Brave Browser, Chrome Browser, Wine and others where you needed to install a third party GPG key and add it, along with using curl to download the repository information should be removed and then re-added for the correct repository. This is because the initial install of those repositories specified the GPG key and just changing the source name is not enough to adjust them to the next release.
Next, ensure all files point toward the repository you upgraded to. In the case of Zorin OS 17, that will be Jammy for Jammy Jellyfish:
sudo sed -i 's/focal/jammy/g' /etc/apt/sources.list
sudo sed -i 's/focal/jammy/g' /etc/apt/sources.list.d/*
Once all is done, in terminal run
sudo apt update