can't open photos in iPhoto after upgrade to 9.5

Given that you're the only person reporting this it's unlikely to be a bug and more likely to be something local to your machine.

What does "can no longer open..." mean? How are you trying to open?

I'm also having the same problem.. I bought the brand new 15" rmbp updated all programs to iLife '11.. In the process of moving photo files to the new machine, but when I openned iphoto, " to open your library with this version of iPhoto, first needs to be prepared." I downloaded the upgrader and it didn''t work either! What should I do?

You need to run the upgrader, not just install it.

I am having similar problems after upgrading to iPhoto 9.5 and Mavericks.

IPhoto opens, but there are no photos or thumbnails or projects. Just about all options are blanked out.

iPhoto does not give me any messages about the library needing updating or being incompatible.

In preferences I choose the default library, but it still does not open them.

My iPhoto library is still intact in the same location it has always been, and is 23gb.

In Finder, if I click on ....pictures/iPhoto library, iPhoto will suddenly launch, and with it all the photos and projects.

Why does it not launch them automatically when I open iPhoto?

Back up.

Try trash the com.apple.iPhoto.plist file from the HD/Users/ Your Name / library / preferences folder.

(On 10.7 or later: Hold the option (or alt) key while clicking on the Go menu in Finder to access the User Library)

(Remember you'll need to reset your User options afterwards. These include minor settings like the window colour and so on. Note: If you've moved your library you'll need to point iPhoto at it again.)

What's the plist file?

For new users: Every application on your Mac has an accompanying plist file. It records certain User choices. For instance, in your favourite Word Processor it remembers your choice of Default Font, on your Web Browser is remembers things like your choice of Home Page. It even recalls what windows you had open last if your app allows you to pick up from where you left off last. The iPhoto plist file remembers things like the location of the Library, your choice of background colour, whether you are running a Referenced or Managed Library, what preferences you have for autosplitting events and so on. Trashing the plist file forces the app to generate a new one on the next launch, and this restores things to the Factory Defaults. Hence, if you've changed any of these things you'll need to reset them. If you haven't, then no bother. Trashing the plist file is Mac troubleshooting 101.