Dealing with a corrupt iPhoto library

There are sometimes when your iPhoto library can, for one reason or another, become corrupt and unable to use. Various symptoms can include your photos not showing up properly (e.g. showing up as gray or black squares), the library becoming unusably slow, or iPhoto crashing as soon as you try to open your library. There are several steps you can perform to try to get your library back into working order.

iPhoto's built-in rebuild function

iPhoto contains a built in method for rebuilding a library's database and/or thumbnails. The steps and results of rebuilding differ depending on what version of iPhoto you're running, and the nature of the problem with your library. Full instructions for doing a rebuild can be found on Apple's site at Rebuilding the iPhoto Library.

Permissions problems

One other common cause of this is that the permissions for your library or its contents have been turned off so that iPhoto can't read the data it needs. To fix this, use iPhoto's built-in permission repair capability, which you can read about on Apple's site at Rebuilding the iPhoto Library.

iPhoto Library Manager's rebuild function

iPhoto Library Manager includes its own rebuild function which can attempt to rebuild a corrupted library based on any salvageable information it can find in the library package. You can read more about this rebuild function here.