Can't disconnect iCloud photos sync, because photos wont open, because library wont load.

As I understand it, you want to keep your Photos in iCloud, and stop synching your Photos with iCloud Photos from your Mac, as the local Photos Library is no longer working?

I would copy your current Photos Library to an external drive, just in case you need to extract photos from it later.

Then delete the broken library from your Pictures folder.

• Now create a new, empty Photos Library in your Pictures folder: Just hold down the options key ⌥ while launching Photos.
• When you see a dialog to select a Library click the "Create new" button.
• Next, open the Photis > Settings (or Preferences) and click the buttun "Use as System Photos Library" in the General tab.

As long as you do not enable "iCloud Photos" in the iCloud tab of the Preferences as well, this new library will not sync with iCloud Photos. You may want to test, however, if you can get the new library to sync with iCloud Photos. It will be much more convenient than having to use the web interface.

Hello DBHartlepool!

I can help clear up how iCloud Photos works for you.

When you have iCloud Photos enabled on your devices signed in with the same Apple ID, your photos are updated automatically across your devices. If you have iCloud Photos enabled on your iPhone and Mac, delete a photo from your iPhone, it is also removed from your Mac. You can learn more about how iCloud Photos works here: Set up and use iCloud Photos - Apple Support

"How iCloud Photos works

iCloud Photos automatically keeps every photo and video you take in iCloud, so you can access your library from any device, anytime you want. Any changes you make to your collection on one device change on your other devices too. Your photos and videos are organized into Years, Months, Days, and All Photos. And all of your Memories and People are updated everywhere. That way you can quickly find the moment, family member, or friend you're looking for."

If you turn iCloud Photos off, they will no longer upload to iCloud and will be stored on the device if you choose to download your photos. If you choose to delete your photos, your photos will be deleted, and you won't have access to them any longer. This article explains in detail about how to download your iCloud Photos and what happens when you do: Download iCloud photos and videos - Apple Support

"What happens when you delete photos or videos

Remember, when you delete a photo from iCloud Photos, it also deletes from iCloud and any other device where you're signed in with the same Apple ID — even if you turned on Download and Keep Originals or Download Originals to this Mac. If you choose to download your originals, this also impacts your device storage. Learn more about how to manage your device storage. You can also learn how to AirDrop your photos and videos to another device."

I hope this is helpful. Good Luck!

I’m sorry too.

Does this excerpt from Can't open Photos App - Photos was unable… - Apple Community help you?

Hi

I finally fixed the problem by the following steps:

1) Booting the iMac into "Safe Mode"

2) Locating the photos library file in Finder (In Pictures on the local start up disk)

3) Double clicking the library file which initiated a "Restore" of the library file.

4) Once the "Restore" completed the Photos App would open successfully.

5) Rebooted into "Normal" mode and verified that the Photo App still open and all the contents were present and correct.

For info the OS was Ventura 13.1 running on a 2017 Retina 5K 27" iMac, with the Photos library file in Pictures on the local Hard Drive (10GB in size).

Local hard drive is a Fusion drive.

I was using iCloud for Photos across all my devices and "Copy items" was clicked in preferences.

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Also check out this excerpt from Photos can't open the library - Apple Community:

Launch Photos with the Option key held down and create a new library, If you can import some Photos into it and confirm that it works as it should. Open and close several times.

If you can create and use a new library then your current library is the culprit. In that case go into your backup and restore the library that was saved just prior to this happening.

I hope this is more helpful in solving your issue. Wishing you the best of luck!!