Q: Lost iPhoto "events" with El Capitan

You may have to research for details in how the Photos app uses

Moments, Collections, Years -- as a replacement organizing method.

Good luck...!

GGot new iPhone and when my MacBook Pro made me upgrade to El Capitan I lost all events in photos.

Photos does not have events as the basic structure of the library. It partitions the library automatically into moments, based on the capture time and the locations of the photos.

Your iPhoto events will have been replaced by albums with the same names as your events. Look for a folder "iPhoto Events". It wil lcontain the albums for your events. This folder will best be viewed from the sidebar.  Enter the key combination ⌥⌘S to reveal the Sidebar.

See this support document:  How Photos handles content and metadata from iPhoto and Aperture - Apple Support

You're welcome