Solved: Mac Photos app "cannot open migrated library" or "library cannot be opened" or "quit unexpectedly" errors fixed

A friend and colleague who uses a Mac just had problems with his Mac Photos app library. First, it's frustrating in this day and age that software still can't be more resilient against such corruption. But I digress.

First thing to try: hold down command and option while launching Photos. This brings up the photo library repair tool, which should handle most issues.

Of course if that doesn't work, you're going to have to recover the photos manually and start over with a brand new library. (Sorry 😞) To recover the photos from your library:

1. Quit Photos if it is running
2. Make a current backup so you can recover to this state should anything go awry
3. Go to the Pictures folder in your Home folder. (Click Go -> Home in the Finder menu, then open Pictures)
4. Right click on the Photos Library and click Show Package Contents
5. Copy the Masters folder out to a safe location (an external hard drive if you don't have space on your built in storage)
6. You may need to repeat steps 3–5 for the iPhoto Library if you have one as well; that will contain any older photos from before the Photos app existed
7. Delete the Library (or Libraries) 
8. Launch Photos
9. Drag the Masters folder into Photos to import the photos back in

And whatever you do, don't go deleting any old iPhoto library on your system. As a part of the migration from iPhoto to Photos app, the developers chose to simply link to the photos already in the old library while adding photos to a new Photos Library. Super confusing, I know. But if you do delete the old library, you will lose those old photos.

Comments

[APC]

Thanks so much for writing these instructions, they've helped a lot!!