Move Photos from NAS to external hard drive

One of the reasons not to have a library on a NAS is that it can damage the library, and this may be the case here. The images may not have actually been copied into the library on import, or the links to them may have been lost. So let's see if we can find them in the library on the NAS.

Right click on the library icon and choose 'Show Package Contents'. A finder window will open inside the library package. Go to the originals folder and within that you'll find a lot of other folders nested. Open each one in turn and sort on date. Can you find the missing images this way?

If you can, drag them out of there and import them to the new library on the external.

I stress you do this only on the library on the NAS. It's not worth anything anyway. If you can't find the missing images there then I'm afraid I would be pessimistic unless you have a back up somewhere else.

Wow-- That's some problem!

I think the first thing that I would do, just to make sure the Photos app is OK, is to create a new Library on the internal drive and import a few pictures to see if everything is behaving normally. You can create a new Library by option clicking the Photos icon.

A Photos Library has the extension ".photoslibrary" -- the default name is "Photos Library.photoslibrary" That name causes the Library to be treated differently than a regular folder of files. One thing you might try is removing the extension. This makes the Mac think that this is just your usual ordinary folder, and you may find it easier to move. If that works, you can just drag it to your external drive and add the extension, so Photos will recognize it as a Library.

Be sure your external drive is properly formatted! To get full functionality (and 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.

If you haven't already, check this reference:

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

Here's an example of a Photos Library Package contents:

This is a Library that has just a few files and which I use to mess around with. Changing anything inside the package could permanently destroy your ability to access the database!

Probably the only folder of interest is "Originals." These should be completely unchanged files of the imported pictures. They have weird, unique names, because original file names like "img_0012.jpg" could occur many times, maybe from different cameras. The original file names, keyed to these unique names, are stored in the database which is inaccessible because. as Yer_Man says, the database has apparently lost contact with them. The dates should be the dates that the files were imported.

If your pictures are anywhere, this is the place to find them.

Try using a back up utility that stores the data without changing it (so, not Time Machine) like SuperDuper or Carbon Copy Cloner. These apps might help with whatever glitch is impeding the copy to the HD. Therefore the process is basically tell the app to "back up" the library to the HD - and remember that HD must be formatted Mac OS X Extended, Journaled or apfs.

That's good news! Glad you got it to work...