However there might be some Problems in running iPhoto again in OS X Yosemite because The New OS X version have Photos App. Open Macs Application Folder in you computer and Launch iPhoto App to check if you want to take further action or not, if you are lucky you will have the App Open just fine and you don’t need to take any further steps. You can go ahead and use iPhoto.
Some OS X users might see the iPhoto icon has a cross through it indicating it won’t open. Even if you try to open iPhoto, most commonly you might get the following error message.
“In order to open iPhoto.app you must update to the latest version”
However if you try to click on the “Search App Store” Button you will get another Error message saying “Item not Available” there is an Easy way to fix those Errors. And in just few minutes you can use the iPhoto App just as you want. just Follow the below Instructions to do that.
How to Use iPhoto on Mac
1. Open Mac App Store
2. In Mac App Store go to the Purchases tab and locate “iPhoto”
3. Now click the “Install” button, next to iPhoto App, this will download and Install the latest version of iPhoto which is compatible with OS X version 10.10.3 and Later.
4. Go back to the mac Application folder and Launch iPhoto as normal, for easy access drop the icon into OS X dock.
The iPhoto App will Open, if have any photo library it will show the Library, if you don’t have any Photos you will be on a fresh iPhoto Screen.
In Mac it is Possible to run both Photo and iPhoto App, but it is not a good idea using both Apps at the same OS might confuse or mess up an Photo library. You should really stick to one App or the other. If you desperately want to use both Apps, make sure to create different Photo Libraries for both App so they don’t overlap while in use.
Remember iPhoto is no longer supported by Apple, the Photos App is the Future of Mac, So moving an iPhoto library to the Photos App and try to learn and getting used to the interface of Photos App is best idea. You can Use IPhoto as long as you want but it is not going to receive any Updates in future. So it may lose compatibility with Future OS X Versions.
Generally, running iPhoto on Mac with Photos App is not recommended, unless you have a compelling reason to do. It is best to use Photos App in OS X Yosemite and move forward.