All photos gone with upgrade to iPhoto 9.6 ???

That is the second case I am seeing here, that the iPhoto upgrade lost the connection between original files and edited versions. Which iPhoto version did you upgrade from?

Unfortunately, we made no backup of our photos ...

Is your iPhoto library included in the backup you make of your Mac, perhaps a Time Machine backup? Then you could try to restore the iPhoto Library from Time Machine.

If that is not possible, use the folder with the recovered items. It will contain all original photos found in the IPhoto Library You can break it down into events by date from the "Events" menu: Select the recovered event and use the command "Event > Autosplit selected events".

1. Make a back up. Make a back up. Make a back up.

Using a computer without a back up is like driving without a seatbelt. You can drive for years with no problem, but the day you do have a problem the mess will be a lot bigger. Upgrading anything OS, Apps, whatever without first making a back up is drunk driving with a blindfold on and no seatbelt.

2. I'm not sure what you've got right now. Is the 500 GB library still intact? If not, then really you're next job is to start over from scratch. Make a new Library and start importing all those photos again.

3. If you do still have that 500 gb library intact, then try Download iPhoto Library Managerand use its rebuild function. (In early versions of Library Manager it's the File -> Rebuild command. In later versions it's under the Library menu.)

This will create an entirely new library. It will then copy (or try to) your photos and all the associated metadata and versions to this new Library, and arrange it as close as it can to what you had in the damaged Library. It does this based on information it finds in the iPhoto sharing mechanism - but that means that things not shared won't be there, so no slideshows, books or calendars, for instance - but it should get all your events, albums and keywords, faces and places back.

Because this process creates an entirely new library and leaves your old one untouched, it is non-destructive, and if you're not happy with the results you can simply return to your old one.

4.

It has to be noted, that iPhoto regularly complained about inconsistencies before, which have been repaired.

If that happens once then it's not a problem, but when you get a message like that "regularly" then there is an underlying damage that's not being fixed.

Well somewhere on your Mac are those 120,000 images.

Start with the biggest library package. Right click on it, Select 'Show Package Contents' and look in the Masters folder there.

In this folder "iPhoto recovered photos", there are roughly 121,000 files but thereof 45,000 are thumbnails and every second file has the suffix "face" which shows only the marked face. So these are definitely not all original photos found in the iPhoto Library.

Recovery software will only create a large folder with all photos, and probably not even be able to retrieve the file names or dates. You are much better of the Masters folder in your iPhoto library, if it still holds all original photos.

The 500 gb library is gone, the current one has just 2.7 GB.

Is 2.7GB what you are seeing in iPhoto or in the Finder, when you look at the file size of the library?

I am in a similar state, only just half-way gone. I just upgraded to iPhoto 9.6 from the immediately previous version (9.5). ALL of my albums are gone and nothing is shown in the new library. I can still see my photos in the iPhoto Library in what is now a file structure even more full of older version artifacts:

Old Masters

1997/

1998/

1999/

2000/

2001/

2002/

2003/

2004/

2005/

2006/

Attachments

Auto Import

Backup/

Contents/

iLifeShared/

Info.plist

iPhotoAux.db.bak

iPhotoLock.data

iPhotoMain.db.bak

iPod Photo Cache/

Library.cache

Library.data

Library.iPhoto

Library6.iPhoto

Old Previews/

Old Thumbnails/

ProjectCache/

ProjectDBVersion.plist

Projects.db

Recovered Photos/

SlideshowAssets/

ThemeCache

AlbumData.xml

Data/

Data.noindex/

Database/

iPhotoAux.db

iPhotoMain.db

Masters/

Modified/

Originals/

Previews/

Thumbnails/

Insanity. I am going no further, in case all my photos are then erased.

It may be time to abandon iPhoto, which was becoming very slow with my 22,000 photos and increasingly hard to work with. Just try to edit the locations of photos on the little map! A truly insane effort. Faces was fun but really not necessary and ate lots of CPU time.

MacBook Pro (17-inch, Late 2011), Yosemite 10.10, 2.4 GHz Intel Core i7, 8 GB 1333 MHz DDR3

Download iPhoto Library Managerand use its rebuild function. (In early versions of Library Manager it's the File -> Rebuild command. In later versions it's under the Library menu.)

This will create an entirely new library. It will then copy (or try to) your photos and all the associated metadata and versions to this new Library, and arrange it as close as it can to what you had in the damaged Library. It does this based on information it finds in the iPhoto sharing mechanism - but that means that things not shared won't be there, so no slideshows, books or calendars, for instance - but it should get all your events, albums and keywords, faces and places back.

Because this process creates an entirely new library and leaves your old one untouched, it is non-destructive, and if you're not happy with the results you can simply return to your old one.

Tried this, and no luck. I received the warning:

Rebuild Complete

No photos were imported

Despite this message, the library folder referenced and also shown in bottom left corner under iPhoto Library Information shows a library size of 584 GB (which is correct to my memory).

That means your database is hosed beyond repair. Time to restore from your back up.

I am frustrated with iPhoto 9.6 as well. I too was forced to upgrade to 9.6 because I upgraded my iMac to Yosemite. Everything seemed ok at first but then my Mac's power crash problem resurfaced (didn't happen in Maverick but was frequent in Mountain Lion) and it happened when I was using iPhoto (seems like it caused the mac to run very hot). Every time it crashed, the iPhoto library would be completely messed up. The repair option it offered when application was relaunched did not help. It would just say library was used by another application. The only way to reopen the library is to rebuild it. Click the iPhoto icon while holding the command and option button at the same time. That pops up the repair/rebuild screen. Select rebuild database option. That at least seems to allow me to see all my photos. I don't know if the multiple rebuilds has somehow messed up something else or there is another bug. Many of the thumbnails in a lot of my albums are messed up. Most of the pictures in portrait mode now show the thumbnail images stretched in landscape form. You have to double click to enlarge and then manually rotate back to portrait. After returning to thumbnail view the picture would sometimes restore back to normal. I am in the process of exporting all my 11K photos to separate folders (corresponding to my album names) on a backup drive. The exported photos seem to be undamaged. I don't want to risk losing everything when all 11k photos are stored in this one big 55GB iPhoto library file.

The Library is not a file, just a special kind of folder. But you must always have a back up.

You have an issue on your machine that is not related to iPhoto - that it's running hot and crashing a lit - and you should get that checked out.

This is a 6.5 years old iMac that is under power and under memory. I probably will replace it soon. I have everything backup in Time Machine. If iPhoto library is a special kind of folder and I can't access it other than from iPhoto then the risk is the same. I can't access the photos if the library is not corrupted beyond repair. If there other ways to access the individual photos without iPhoto? I remember years ago, they kept photo files in different folders. Some time ago (don't recall which version) turn this library into one gigantic file (special folder). Now iPhoto seems to have lost all photo orientations. All portrait photos are messed up even in enlarged mode. The exported file opened in Preview is fine but I have to reorient the photo back to portrait. It seems to be happening to all photos that were converted from the old version library. All new photos imported directly into the new 9.6 version seem fine. I may just reimport the rest of 11K pics once I have a new machine. I don't look forward to reorienting however many portrait photos I have in my collection. That is my frustration.

Had exactly the same issue !!! a nightmare !

If iPhoto library is a special kind of folder and I can't access it other than from iPhoto then the risk is the same.

But you can access it from the Finder just remember that it's not supported and you risk damaging the Library.

Your Library is made up of a number of elements: the actual photos and the database that tracks them are the principal elements. If the database is damaged it does not mean that the photos are - but the iPhoto window will be empty, or all the other issues that you are describing. The question you need to ask is why this keeps happening to you and not other folks?

To look inside the Library: same as every other package on your Mac: Right click on it and select 'Show Package Contents'.