You say, "When I try to export or double click a photo I get the above message." You also say, "when I double click the photo it still opens up the photo in all its glory." Does it do both things with a double click? What does "in all its glory" mean? We need to know, really, what you mean. What, exactly, are the steps you use? Some other information you should include:
- Are you using macOS 10.13 High Sierra, from 2020, as you signature says?
- You refer to iPhoto, an application that was discontinued 9 years ago. Is that right? Or are you using Photos?
- Can you edit the picture? What happens when you choose Edit mode?
- What happens when you use File>Export>Export Unmodified Originals?
- Are you, in fact, using a Referenced Library? Do you have "Copy Items to the Photos Library" checked, and has that always been checked?
- If you run a Smart Album with "Photo==is==Referenced," what do you see?
- If you have referenced originals, have you tried re-connecting them with File>Consolidate? Have you tried finding the originals?
The database connects original images to editing and annotating information and thumbnail versions. There may also be preview versions that are screen sized, look good, but aren't full resolution.
