Repair your library in Photos on Mac
If you experience problems with photos in a library, you can try to repair it. If problems persist, you can also restore your library from a Time Machine backup.
Important: You should back up your photo library before repairing it.
If the Photos app on your Mac is open, choose Photos > Quit Photos.
Press Option-Command and double-click the Photos icon in the Applications folder (or click the Photos icon in the Dock).
In the Repair Library window, click Repair to rebuild your photo library.