How do I start the import of Aperture libraries to Photos?

Hi there Gerald Gifford,

Thanks for using the Apple Support Communities. It sounds like you want to import different Photo and Aperture libraries, while having them remain separate and stored in different locations. I’ll be happy to help with this.

If I’m understanding you correctly, you’ll first need to quit Photos, then hold down the Option key and double-click the Photos icon in the Applications folder (or click the Photos icon in the Dock) to open Photos. Click Other Library and location your Aperture Library in the box. Your Photos should start importing and will remain separate from your main Photos library. If you have any issues importing your library, take a look at this article for what to do:

If Photos can’t copy or create a library

Once the import is complete, you can use Photos with your Aperture library like normal. To switch between library, you’ll need to quit Photos, and hold down the Option key while opening it, then selecting Choose Library from the menu that appears. You can read more about this here:

Create additional photo libraries in Photos on Mac

If you want to keep the imported library on your external device, you can use the steps from this link to guide you how to to change where your files are stored in Photos for your Mac:

Change where your files are stored in Photos on Mac

On the chance that you want to combine your existing Photo library and Aperture library, then you’ll want to follow the steps from this link:

Combine libraries in Photos

I hope that gets you going in the right direction for importing and using your Aperture libraries with Photos. Please let me know if you have any other questions.

Best wishes.

Gerald Gifford wrote:

2. Can you explain what's going on with a file with a suffix like "Photos... migration.library" or something? What is it? How do I use it?

After Photos has created a new Photos Library from an iPhoto Library, it will change the filename extension of the library it has migrated from .photolibrary to .migratedphototlibrary. Otherwise the iPhoto Library remains untouched and is still the same old iPhoto Library, just the filename extension has changed. If you want to open it again in iPhoto to compare it to the new Photos Library, you can just double click it. You will be asked, if you want to open it in Photos or in iPhoto. I would keep the original iPhoto Library for a while, so you can look up the items that could not be migrated perfectly to Photos, like the descriptions of albums, or the smart albums. Perhaps there are still phonebooks that you need to save as a PDF or similar. iPhoto will still be working until the next system version will be released.

Sorry I cannot edit my post any longer. What I wrote about iPhoto applies to Aperture as as well.

The Aperture Library will remain untouched, just the filename extension will be changed to .migratedaplibrary .

You can simply rename the "Aperture Library.migratedaplibary" back to "Aperture Library.aplibary" and Aperture can open it again, if you need to compare the new Photos Library to the previous Aperture Library. But if you need to merge Aperture Libraries into one library, do it while you can use Aperture. Merging libraries in Photos is lossy, because it breaks the connection between the originals and the edited versions. The only way to merge libraries lossless in Photos is to upload several libraries to iCloud and they will merge in iCloud.

You can name it anything you'd like as long as the extension remains the same:

Glad to be of help.