Cannot export certain photos from Photos Library without error

Dragging a photo will export the preview of the edited version, so your photos do not seem to have previews. Can you export the originals? If you have not done so, try, if using the command "File > export > Export unmodified original" is giving the same error.

Where is your Photos Library stored? Is it in your Pictures folder or on an external drive?

If the library is on an external drive, you may want to check, if the drive is suitable for a Photos Library as described here: Move your Photos library to save space on your Mac - Apple Support

• The file system format needs to be mMacOS Extended (Journaled) or APFS.
• The Drive must not have been used for Time Machine backups or have any backup software installed.
• The external drive needs to have a wired connection and must not reaccessed over the local network.
• if you cannot set the "Ignore ownership on this volume" flag, something is wrong with the external drive.

If your Photos Library is on the internal drive of your Mac, check, if it has become moved to a synced folder. The syncing can damage the library badly. The Photos Library must not be in a Dropbox folder or on iCloud Drive, or in your Documents folder or on the Desktop, if these folders are syncing with iCloud Drive, or on Google Drive. If your library is in such a synced folder, drag it back to your Pictures folder and hope, that any damage can be repaired, once the library is back in a safe location.

Or have you been running any application to remove duplicates from your Photos Library? Some of them can damage the library badly. In that case you will have to restore the library from the last backup you made before you tried to "clean" the library. If a cleaning app has removed the originals, it cannot be repaired.

It sounds like the Photos database has lost the connection between the pictures and the original file. Picture files are usually stored inside the Library package where they can be "managed" by the database, but sometimes, perhaps inadvertently, the database may make "reference" to files stored somewhere else, and the connection can become lost. This may be what happened. You can see if pictures are "referenced" with a Smart Album, like this:

(By default, Libraries are Managed, not Referenced, so I had to make a special Library to show this.)

Check and see what you get. In that case, the original files may be hard to find-- they could be on your internal drive somewhere, on a backup, or erased.

Double check the General Settings to see if you have checked "Copy Items" is checked-- this is the default setting.

It may be that with your older pictures this got changed, somehow.

Other things I need to ask: Are you using iCloud to sync your Photos Libraries with your devices? Sometimes that connection to the originals gets confused.

Are you using an external hard drive for your Photos Library? If so, how is it formatted? To avoid damaging the Photos Library an external drive must be formatted in either APFS format or Mac OS Extended (Journaled) format. Additionally, the drive can not have had Time Machine on it since it was formatted. There have been so many problems with using incompatible drives that the newest macOSs won't even allow a Library on a non-Mac formatted drive to open, since there is a chance of damaging the Photos database. See this:

Move your Photos library to save space on your Mac - Apple Support

Let us know...

To test OT's suggestion about a referenced library you may want to create a smart album to show you any referenced photos:

• File > New Smart Album
• Set the rule to "Photo > is > referenced".

Is this smart album empty? If not, you may have to reconnect the referenced files.

A while ago I did run Duplicate Detective though that was quite a while ago and this issue only surfaced recently.

That may be the answer to your problem. It may have removed the original file leaving the lower resolution preview file that is used to display edits, etc.

I have done that is successful is to search for the filename in spotlight. When I do that, I can locate the file and use it outside of the Photos app.

Since Spotlight can't search within Photos Libraries those files must be located somewhere outside. So that brings up the question are you running an "managed" or "referenced" library. The managed option might have been turned off temporarily due to a system update or upgrade.

" When I CMD-I, I realize that the location of the file is actually in my old iPhotos Library, which hasn't been updated in close to 10 years."

That is what I suspected. When Aperture 3 and iPhoto '11 came out and Apple made the libraries compatible for both applications, there has been a short period, when we could migrate iPhoto Libraries to Aperture, while sharing the originals in iPhoto with Aperture. We then had to keep the Aperture Libraries and the iPhoto Libraries on the original volume, or Aperture could no longer find them. These shared mongrels did not show in Aperture as referenced files. As none of my current Aperture libraries has been migrated this way, I cannot test, if Photos can handle this properly.

You could try to import the iPhoto Library with the originals into your Photos Library with the missing originals. Photos on Ventura can import photos directly from iPhoto Libraries and Aperture libraries.

• Open library you want to import the items to in Photos.
• Then use the command "File > Import" and select the iPhoto Library for import.
• Click the blue button "Check for Import" (or similar - my Mac is currently set to German as the system language).
• Now wait for the missing photos to appear in the import window. This can take a very long time for a large library. It may help to close all other apps that you do not need while you are working with Photos to free some memory, if the library is large.