Revert Sierra Photos Library to El Capitan format
I installed the Sierra Public beta on an external drive i use to test such thing on my imac.
I, not so cleverly, said yes when it asked me if I wanted to try the new Photos app. It latched onto the other external drive with my default 1.2 TB photos library. Now I can no longer access the Photos library from El Capitan. I am downloading the previous version from Crashplan but that is going to take a couple weeks.
My external Photos library was converted from the Yosemite to the Sierra format and can no longer be opened from Yosemite. Sierra Photos libraries are not compatible with the Yosemite version of Photos. I wondered if there was an easy way to change it back to the Yosemite version.
To be clear, the problem is not pointing Photos to the old Library. I know how to switch libraries. The problem is converting the Photos library back to El Capitan format from the Sierra format.
Is there an easier way roll back the Photos library to being El Capitan format? (No it is not in my Time machine backups. My bad.)
Thanks very much for an help or suggestions.