Transferring Photos Library from macOS Sierra Public Beta to macOS Sierra I have a 40GB Photos library on my 2010 13" Macbook Pro, which is running macOS Sierra Public Beta. I just purchased a new 2016 13" TB Macbook Pro, which is running a stable release of macOS Sierra (10.12.2). 

I copied my Photos Library from one to the other, thinking it'd be a simple switch. My new machine however refuses to recognise the library, I'm assuming because the library was used on a machine running the (more "up-to-date") beta.

My question is, what's the simplest way for me to import my photos into my new machine? will I have to resort to putting it on the public beta as well?
It's not possible to open a library from a newer version of Photos using an older version of Photos. Photos will inform you of the version discrepancy when selecting the library. If you receive this message, you need to either use a backup of the library made prior to updating Photos, or update Photos to match or be later than the library.