If you’re upgrading your OS X and you iPhoto library is quite large and the migration happens to fail, you may see an error in finder saying your library had already been migrated, but there are no photos in your Photos App!
No need to Panic! Just navigate to your old iPhoto library in finder, right click and open info, remove the .migrated from the file extension, close the window, re open your library and migration should restart and you’re on your way!
KB.
