Photos App

Hello and welcome to Apple Support Communities, timcarless!

I understand that whenever you select a duplicate photo in the Photos app, it quits. I'd be happy to provide information to help you troubleshoot this issue.

Try the applicable steps in this article first: If an app freezes or quits unexpectedly on Mac

Then if the issue persists, try selecting the photo in safe mode: Use safe mode to isolate issues with your Mac

Thank you for using Apple Support Communities.

Enjoy your day!

1 - As a test launch Photos with the Option key held down and create a new, test library. Import some photos and test to see if the same problem persists. Does it? (This tells us if the problem is limited to your current library or is more wide spread).

2 = next open your current library and test again.

3 - if you're still getting crashes log into another user account on your Mac and run the test in #1 above. This will tell us if the problem is limited to your account or is system wide.

Is it a particular photo or any photo? Where is your photo library located?

I suggest you start Photos with the option key held down and create a new library on the local drive. Import some images. Can you duplicate from the new library?

An in-elegant work around would be to export the photo and re-import it.

Yes, your primary library is the existing/problematic one.

The repair procedure starts automatically but the key combination to hold down is the Option+Command keys.

You'll get this

Open your primary library and then close Photos. Hold down the Option key and launch Photos. When you library comes up let the repair procedure go thru.