Photo App won't open after I downloaded OS X El Capitan V.10.11 Photo App won't open after I downloaded OS X El Capitan V.10.11. 
Response: "Photos must quit because the photo library has become unavailable or its data is corrupt."
To bypass this, hold down the Option key as you open the Photos app. You will get a dialog box letting you choose other (i)Photo libraries, or open a new, blank library: