can't open iphoto v.9.5.1.
when i open, it said:
"To open your library with this version of iPhoto, it first needs to be prepared."
i click learn more,
then it direct me to apps store and i install the upgrader, but problem still exist.
Are you saying you downloaded the Mavericks compatible version of iPhoto 9.5.1
You can find it in your applications folder along side the older versions. Drag it to the Dock for convenience.