Update Photos app to purchase photo book project

Apple does no longer offer any print services. To be able to order books from Photos, we now have to install third-party applications, that provide project extensions and then create the books with these extensions. Project extensions are available from the AppStore, if you upgrade the Mac to macOS 10.13 High Sierra with Photos 3.0 or better macOS 10.14 Mojave with Photos 4.0.

Photos is a part of the system and can only be upgraded by upgrading the system. (Post 9/30/2018 Printing Options for Photos )

But, as your book is already finished, you may want to export the book as a PDF file and then upload it directly to a service, that can print Apple Books from PDF files. Ordering Books and Calendars on a Mac tha… - Apple Community

To save your finished PDF book as a PDF file see: ( Check and review a project before you order using Photos on Mac - Apple Support) and then send it to a service that can print books from PDF files.

• Mimeo used to print for Apple and can handle PDFs created in Photos, see: https://import.mimeophotos.com
• Also Presto Photo can print from Apple https://www.prestophoto.com
• If you are not located in the US, there may be local printing services, which would be more economic with respect to international shipping fees and shipping time. In Germany we can use photographerbook to print existing Apple PDF files: https://www.w2p-photographerbook.de/fotobuch-aus-aperture-iphoto-fotos