How do I upgrade my iPhoto library on Yosemite??

I downloaded Yosemite and the new iPhoto that is compatible with it. I'm able to open iPhoto, but then I get a message saying I have to upgrade my iPhoto library. When I try to do this, it will start "examining my library" but then iPhoto will stop responding and I have to force quit. How do I fix this?? I want my pictures!