Getting Faces from iPhoto to Photos

I just tested again and opened an older iPhoto Library in Photos.

I am seeing all faces I named in iPhoto in Photos, when I click the "People" album in the sidebar, and then click the button "View People Album", even if Photos is still showing "0 Photos Scanned".

What are you seeing, when you click "View People Album"?

Have you already activate the option "View > Show Face Names" in the View menu in Photos, so you can see all faces circles overlaid on the photos, that have been detected? My screenshot is from Photos 4.0 on Mojave, but it used to be similar on High Sierra.

Smatt albums do not transfer well between iPhoto and Photos.

If you want to repeat the migration, I would use your smart albums in Photos to assign a keyword with the name of each person to the phots with named faces. The keywords will transfer well, and you can use them after the migration to search for the person and recreate the named faces quickly.

If you are using iPhoto and faces name should not be removed when you convert iPhoto into photo library , export the complete iPhoto library to an external hard drive ( the exact library will be exported with all your family faces with their names also the smart albums see this article iPhoto: Back up your iPhoto library

And then import the library see this article Overview of importing photos and videos into Photos on Mac - Apple Support

See some general articles iPhoto: Remove people from your Faces corkboard

My test library has been small, just 100 photos, so the faces scan finished quickly.

Let the Mac run over night, connected to Power, with Photos minimized in the Dock, so it can finish the Faces scan and the face recognition. It may take several days for such a large library. When Photos has finished the faces scan, help it along by putting names into a few of the empty faces names. Then use the "confirm additional faces" at the bottom of the faces album of your son. Photos will be showing the faces there, where it is not quite sure, if it is really your son.

The problem is, that the face detection algorithm in Photos is very different from the face detection in iPhoto, Aperture, or even older versions of Photos. So the faces circles detected by Photos may be in a slightly different position than the faces circles previously detected by older software. Photos will only use the faces circles it detected itself with the current version of the face detection, and we have to help it initially by assigning faces to a few of the new faces circles, to get it started, if they are not matching perfectly the migrated faces. If the previously detected faces are matching perfectly, they will be used. I had to do that even again after the upgrade from Photos 2.0 to Photos 3.0. , whenever the face detection algorithm changes.

That is why I got into the habit of assigning keywords with the faces names to each photo. The keywords are in the long run much more stable than the faces names and survive the upgrades of the face detection algorithm.