how to transfer iPhoto library from old macbook pro

You could try & manually use migrate to move (copy) data from one Mac to another...

Not all items from an older Mac or its OS X should be moved into a new one. Be wary.

• OS X: Manually migrating data from another Mac - Apple Support

There is a section in the above that says what to try once you have the iPhoto library

moved into the Photos folder, and if that isn't recognized, a link to info on what to do.

• How to Move an iPhoto Library into Photos for Mac:

http://osxdaily.com/2015/04/17/move-iphoto-library-to-photos-mac/

Be sure to make backups and separate archives for your computers so they won't run

out of storage space; and an adequately sized drive device for Time Machine, too.

Here's a fair source for information that can be useful, beyond the photo libraries inquiry.

• Apple OS X and Time Machine tips:

http://pondini.org/OSX/Home.html

Good luck & happy computing! 🙂

Connect the two computers together (network, FireWire Target Mode, etc) or use an external hard drive formatted Mac OS extended (journaled) and drag the iPhoto library from the old computer to the Pictures folder of the new computer - launch Photos on the New Computer and it will migrate the Library to the new software

Prior to doing this read there

Notes on Migrating an iPhoto Library from iPhoto to Photos for Mac

How Photos handles content and metadata from iPhoto and Aperture - Apple Support

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