MacOS Photos app - missing files: find originals

I'm thinking there needs to be some clarification of what's going on with your pictures. Excuse me if I'm just repeating what you already know:

The idea of Photos is to keep the Original Picture file forever unchanged. When you edit a picture, annotate it, or put it into a folder, nothing happens to the Original. Photos keeps a database, like an Excel spreadsheet, that connects the original picture to each of the things you've done to it. Photos makes thumbnail images and small preview images to allow smooth scanning through pictures, and those, too, are connected to the originals with the database. When you zoom in, or edit, or print a picture, Photos goes back to the original files and re-applies all the edits on the fly to make the picture you thought you had. The original is never actually changed, and full edited pictures aren't stored.

Usually people have Photos store the originals inside the Photos Library so Photos will always know exactly where they are. That's called a Managed Library. But sometimes, people want to keep their pictures in Finder folders rather than inside the Library, then called a Referenced Library. The downside of a Referenced Library is that Photos can lose track of the Originals. We always advise against a Referenced Library. Somehow, unfortunately, some of your pictures are Referenced, and the connection to some of them is lost.

Your problem is that Photos has the thumbnails and some Previews, but it can't connect them with the Original files. That's why you can see the pictures, but you can't do much with them. So you need to find those originals and re-connect. In Photos' menu File there is the choice "Consolidate" which can help with that. It copies the referenced files into the Library. You have 8000 of these "Referenced" pictures that are lost because they were not copied into the Library. Some of your Referenced pictures may not be lost-- they may still be available to Photos. So you should try the Consolidate command. Then check your Smart Album and see if the number has gotten smaller, as some Referenced files have gotten connected.

If you can find any of those old files, on a CD or DVD or an old hard drive, you may be able to point Photos to where it should find the pictures, and let it Consolidate more.

If the files have been copied into the library, when you imported to Photos, the originals are stored inside the Photos Library package, but Photos has lost the connection.

This damage cannot be fixed by reconnecting the originals.

As a test, you may want to create a smart album (File > New smart Album ⌥⌘N") with the rule "Photo > is > Referenced". If the album is not empty, the items have been imported as referenced, and you should be able to reconnect them. But if the smart album is empty, your Photos Library is damaged.

In that case you could try to repair it. But you have to make sure, that the Photos Library is in a supported location.

• If the library is on an external drive, the external drive needs to have a compatible file system forma (APFS or Mac OS Extended (Journaled). The drive needs to be connected to a USB port, do not use a NAS. And the volume must not have been used for Time Machine backups, see: Move your Photos library to save space on your Mac - Apple Support
• If your library is in a folder on the internal drive of your Mac, the Pictures folder would be the best place. The library must not be in a folder that is syncing with some cloud service. It must not be on iCloud Drive or on your Desktop or in Documents, if these folders are sinking with iCloud. Do not keep the library in a Dropbox folder either.

The library could also have become damaged by tools to remove duplicates. Such a damage cannot be fixed. you would have to restore the library from the last backup you made before you let some duplicates cleaner touch the library.

Can you tell us more? How have you imported the photos to Photos? Did you import them by copying the photos into the library or is Photos referencing the originals outside the Photos Library? Your Photos will be copied into the library, if the Photos > Preferences > General > Importing has been set to “Copy items to the Photos library”.

Otherwise the originals will be referenced in the original location and must not be moved. Change where your files are stored in Photos on Mac – Apple Support (UK)

Try to find one of the missing files by searching your Mac for the filename in question.

If you can find one of the originals and reconnect it, Photos might automatically reconnect all other originals in the same folder. Otherwise Photos has no tools to help you to fix all broken references at once.

The consolidate feature is only available, if the image file has been imported das referenced, not if the original cannot be found for some other reason. Typical reasons are a damaged Photos Library because of a failing drive or similar, or a library corruption by running cleaning applications, external photo editors, that are writing back to the Photos Library, but incorrectly.

If Photos expects the original image file to be in the library, it does not offer the "consolidate" command.

You could try for a few photos to import the originals again and see what happens. Occasionally I have seen that this has fixed a missing original. Import them, even if Photos is warning about a duplicate.

Have you enabled the options in the View > Metadata menu? If not, enable "Referenced" and "File Type". You should be seeing an arrow badge for referenced images on the thumbnails, with a broken arrow for referenced images with missing originals. If there are no arrows your image files have not been imported as referenced and consolidate will not be possible.

We expected that most of those files would not Consolidate, but congratulations on the 300 that did!

As léonie has said, you need to find at least some of those originals in old backups, and see if you can re-establish connections. I recently had to go back through old CDs and DVDs and hard drives, some of which weren't 100% readable anymore, to find originals to reconstruct a Library's pre-2006 pictures. Not fun, but satisfying.

That's great! Congratulations!