I'm using the Mac Photos app on macOS Catalina (10.15.4)
I have a Photos library that dates back to 2007 and was originally an iPhoto library. Ever since it was migrated to a Photos library, there have been issues with exporting photos from late 2013 through mid 2015.
When I choose File > Export on these photos, I get an error message:
The export operation failed to create a file for the photo identified below:
Example.jpeg Unknown Error (4)
When I click Reveal in Finder, nothing happens.
I have checked out this Stack Exchange article which describes the same problem I think: How can I repair missing referenced photos in Photos.app on MacOS Catalina?
However, when I open photos.sqlite in DB Browser for SQLite the ZFILESYSTEMBOOKMARK table is empty and the ZPATHRELATIVETOVOLUME table does not exist.
Basically, a large number of my photos exist in the Photos library but can only be accessed in Photos. They cannot be exported. Ideally, I would like a way to find where Photos is storing those files so that I can either repair the database or re-import the photos so that they work correctly.