I've been dealing with an iPhoto library issue after attempting to access my iPhoto library on an older Mac (that at the time had OS X Mavericks installed) via my home network with a new Mac Mini that came with Yosemite. I wasn't even able to open on the original Mac that the library was located on (the one with Mavericks installed) It recommended I download the iPhoto library upgrader, which I did and ran, but without success. I got stuck in a do-loop, with the upgrade telling me "You can't open your current photo library using this version of iPhoto, and iPhoto itself saying "To open your library with this version of iPhoto, it first needs to be prepared." So next, I tried a Time Capsule restore to the previous day on the Mavericks computer, to no effect. I deleted and reinstalled iPhoto. I finally had to download and upgrade the Mavericks Mac to Yosemite, with the latest iPhoto version. I tried the fix you mentioned on this post, of deleting certain user preference and containers, to no avail. I never get the 'first aid option' - it never shows up, just the same message as above when I opened iPhoto. I downloaded the free iPhoto Library Manager, and can now see my libraries, and am about to rebuild them from a backup I have on an external drive (this backup was made after the issues started, however). To free up space on my hard disk, I will have to delete the original that is stored there (the one I backed up). This is my last try, do you have any other suggestions to get iPhoto and the upgrader out of this loop? By the way, the iPhoto manager says the library I'm trying to open is 7.1.5 Thanks.