Problem switching from iPhoto to Photos - library on external drive
Hi,
I tried to get into iPhotos today to find the application disappeared along with my entire photo collection!
My iPhoto Library is on an external drive. When switching to Photos it says: "Photos was unable to make a copy of your library before preparing it. Photos does not have the necessary permissions...".
The support page tells me what to do if iPhoto Library is in the default location but mine isn't.
Please can somebody tell me what I need to do?
iMac, OS X Yosemite (10.10.3)