After MacOS Sonoma update, Photos app is unable to open my Photos Library because it's stored in iCloud Drive.

This was super helpful and worked for me. I had to open two different finder windows and then searched for "library.photoslibrary" in one and "Pictures" in the other. I might have created this pictures folder myself at some point so you may have to create your own "pictures" folder for this to work. Then I dragged the photos library icon into my pictures folder. It took a few minutes but now when I click my "photos" icon in my toolbar, it works.

The Photos application is located in your Applications folder.

To find out where your library is located launch Photos with the Option key hed down and when you click on a library in the Choose Library window it's location will be shown just below the section box:

Just so you know a Photos library must be located on a local volume that's formatted either APFS or OS X Extended (journaled) and, if on an external drive, connected directly (by cable) to the Mac.

If your Photos Library is also on iCloud Drive, drag the Photos Library in the Finder from iCloud Drive to the Pictures folder or another folder in your user home folder. You may get a warning, if you really want to remove the library from iCloud Drive. Confirm this.

If you want an app where everything lives in the Cloud then check out Adobe Lightroom CC. It will cost you, but then you pay you get more options.

David Estes wrote:

In my Photos app I have selected the preference to "Download Originals to this Mac." Shouldn't that be the same as storing copies outside the Photos app folder?? Doesn't seem to work.

"Download Originals to this Mac." is telling iCloud Photos to download all originals from iCloud to your Mac and not to use the "optimize Storage" option. The downloaded originals are stored inside your Photos Library and not in a folder outside the library. All originals will be mirrored on your Mac and you will have a complete photos library and can work with your photos, even without an internet connection. And Time Machine can make backups of your photos. It is the way I like to use iCloud Photos, just for syncing my devices, not for saving storage.

Photos has an option to store the photos outside the library and referencing them in the original location, but then you cannot use iCloud Photos. This is controlled by "Photos > Settings > General > Importing: Copy items to the Library". It is a left-over from iPhoto and Aperture, when we could import photos without copying them into the library and reference them in the original location. If Photos would not support this we would not have been able to migrate iPhoto and Aperture Libraries to Photos. But I cannot recommend to use Photos this way. There are no tools to relocate the referenced files to a different external drive when we need to replace the drive because it is failing, or when we need to restore referenced files from a backup. After migrating a referenced library to Photos we should instantly consolidate it and turn it into a managed library. It will be much easier to maintain, particularly, if we want to be able to sync the Photos Library with iCloud Photos between our devices.

My photo library has been happily sitting on my iCloud drive ever since there was an iCloud drive. I never had an issue with it. In fact that was a reason i opted for the 2TB monthly fee. Now the sonoma upgrade forces me to move it locally where i really have no room for it, so i have to attach another drive to a usb port which i don't have so I have to attach another usb hub to my existing usb hub! And for the entry level macs with small drives there has to be constant resolution conversions (optimizations... HA!) for image manipulation? Why am i not convinced that this is progress in this day and age that EVERYTHING else lives on the cloud?

Please enlighten me!

Is the Photos Library on an external drive used for Time Machine backups? Then Photos cannot work with it, because Time Machine volumes are having limited access rights. In that case you would have to move the library to a different external drive.

There will be no synchronization between a library on the iCloud Drive and a local drive. You can periodically copy the local copy to the iCloud Drive for backup, but you should also have a few other backup sources, too.

1. When I try to move the photos library to a different folder I get a message saying that my IOS devices will no longer be able to access the photos. On top of that, I will now have to download 29GB back onto my computer which will take quite some time and wifi bandwidth. So what gives?
2. What settings do I need to change in order to sync photos across my devices AGAIN, because the fact is it worked before, and my photos were happily residing in iCloud, but now they will both be not in iCloud AND not syncing across my apple devices - devices I bought partially BECAUSE they sync things across the devices. Sorry for the annoyed tone but this is really a nuisance and not at all the Apple experience we've come to expect and enjoy.
3. The icon next to my photo library in iCloud says it's "ineligible" for download - it's a cloud that is crossed out. What does that mean? What in the world is going on?
4. So now because of this "upgrade" I have to do a bunch of manual tasks that are not clear and it feels just like the days of Windows, a big drop of the ball here by Apple.
5. I think I speak for many people when I say that this is terrible on all fronts

I legit just used this fix on my mom's laptop - had no idea what I was doing and you saved me! Thank you! Her photos library file was already on her desktop - I couldn't figure out where to find it, so I'm glad it was just sitting there for me. For other people like me who have no idea what you're doing - you can get into the hard drive by opening Finder, hitting "Go", and then click the little computer icon. Then you can get to the users, go into the pictures and move that library over. It worked!

Hi, How did you move the photos to your hard drive? Thank you.

Completely agree. Apparently we have to have the photo library on the hdd it can't be stored on the icloud drive which mine has been successfully for years! Very annoying Apple.

Ok, good enough.

You might try restarting in Safe mode, that clears some caches and sometimes fixes odd issues like this.

I got this same error message trying to use Photos after the MacOS Sonoma update. I'm struggling to find my photo library on my iCloud Drive though. I'm not sure what I should be looking for - there's no folder there named Photos or any other folder that might look like it might be hosting my photo library. Can I search for it in Finder? Is it named Photos or Pictures or ?