Photos freezes after trying to change System Photo Library
I exported my photo library into an external hard drive to save space on my Mac following the steps on article: https://support.apple.com/en-us/HT201517. But when I try to designate the library in the external hard drive as the System Photo Library, the Photos app freezes, the rainbow circle appears and when I right click the icon it says the app is not responding.
MacBook Pro 15”, macOS 10.15