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About the System Photo Library

If you have multiple Photos libraries, at any given time there will be only one that is designated as the System Photo Library. This library is the one that is made available by macOS for other applications to access directly. This library will appear in the photo browser in apps like Mail, iMovie, and Pages, as well as other services like your screen saver preferences. Applications that offer to import into Photos will import into the system library. The system library is also the only library that can be synced with iCloud.

To specify which library you want to be the system photo library, open the library in Photos, open the preferences window, and click the “Use as System Photo Library” button. (if the button is disabled, that means the library is already the system photo library) Simply opening a library in Photos will not switch the system photo library, so you can feel free to open and work with other libraries without changing which library is set as the system photo library.

For more information on the system photo library, visit this support article on Apple’s website.

macOS 10.13 High Sierra bug: You may have received a message from PowerPhotos when attempting to copy photos or merge libraries saying that you don’t currently have a system photo library set. The reason this warning is in place is due to a bug in High Sierra which will cause Photos to hang after opening a library and trying to import photos when no system photo library is set. Follow the steps above to designate one of your libraries as the system photo library, and that should work around the hanging bug. It doesn’t matter which library you choose, or you can even create a new library and set that one as your system photo library.

Because PowerPhotos needs to use a different method to read the content of the system photo library, you may see some minor differences in behavior when viewing the system photo library versus your other photo libraries:

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