Apple has released iPhoto 9.6.1, which improves compatibility when migrating iPhoto libraries to the new Photos app in Mac OS X Yosemite 10.10.3 — which will be available this spring.
It also fixes an issue that caused iPhoto to display only the first 25 images in a Facebook album, as well as an issue that could cause iPhoto to become unresponsive when printing an image. You can download the updates from the Mac App Store under Updates.