How do you upgrade photos?

Photos is apart of the system. Each version of the system installs automatically the correct version of Photos for this system. You do not update Photos separately, only the Photos Library will need updating to the new version of Photos.

If you just installed the final release version of Catalina, your Photos application is as upgraded as it can be at the moment. Unless you have been running beta test versions on this computer, or you somehow kept and launched some older version of Photos, you should not be getting this message.

How have you been launching Photos? Sometimes the icon in the Dock or an alias on the Desktop are still linked to an older version on some backup drive.

Launch Photos directly by clicking the icon in your Applications folder. This way you will be sure to launch the version that came installed with the current system version.

Sorry, I meant to write "Photos is a part of the system".

Does the message say you need to upgrade the Photos program or the Photos library? What's the exact wording?