Photo app shows "Photos cannot find the System Photo Library named “Photos Library.photoslibrary”".

dexter_y_ximena wrote:

I'm using a Mac desktop and MacOS Sequoia 15.2

When I select Photos/Settings/General/Use as System Photo Library, I get a message "This action will disable iCloud Photos".

I want to use iCloud Photos, so that's a dead end for me.

That is right - if a different Photos Library is currently your System Photos Library and syncing with iCloud Photos, iCloud Photos will be disabled for that library, because only one library can be the system library and sync with iCloud. So you have to make sure, that you have currently opened the correct library, the one you want to sync with iCloud, before you make it your system photos library. In the "general" tab of the Photos > Settings click "Show in Finder" to see which of your Photos Libraries is currently used by Photos. If it is the correct library, the on you want to sync with iCloud Photos, click "use as System Photos Library". Once it is the System Library, you should be able to enable iCloud Photos for this library.

You are seeing the warning, because it is an expensive operation to switch between two different libraries for iCloud Photos. Whenever you turn on iCloud Photos again, if it became disabled the complete library will need to be compared t and synced with iCloud again. This can take several days for a large library. we should not turn off iCloud Photos for a library just for the fun of it. It should be the last resort when trouble shooting.

The same goes for repairing a Photos Library, if it is syncing with iCloud Photos. After a library repair Photos may have restored missing items with broken links and the complete library may need syncing again. So don't repair an iCloud Photos Library, unless nothing else helps.

dexter_y_ximena wrote: … I'm uncertain how I can find other libraries to choose from.

Three ways:

1: Use Finder-- you tried this, but the search was too specific. Search for ".photoslibrary"

I have a bunch. The path to each one that you highlight is shown below.

2: Close Photos and then option-click on the Photos icon. You should get the Library Chooser dialog:

Again, I have a bunch. This shows all the Libraries that Photos knows about.

3: Check the Trash and iCloud Drive. It's not supposed to be in either of those places, but sometimes those things try to commit suicide on their own.

Let us know what you find…

Hi - The same thing on my new MacBook Air.Not sure when they disappeared but phoned Apple Support today and they sorted this. I had to click on Photos, settings, under General Tab click 'Use as System Photo Library', then click on the iCloud logo above this and put a tick in the iCloud Photos box. All fixed after that. I hope I've remembered the correct steps..... Good luck.

If you quit the Photos application entirely with Command-Q or Photos menu > Quit Photos, then launch Photos again while holding down the Option key, it is supposed to give you a list of all the openable libraries it can locate and other options. It might also show you some non-openable libraries with hints why.

What do you see when you try that? Just the "Syndication" library?

Sorry I couldn’t help. It’s a drag when things go missing. Here’s a link from an email the girl from Apple sent me yesterday. It might help. I didn’t do it this way as she looked at me screen and told me what buttons to press.

Designate a System Photo Library in Photos – Apple Support (UK)

You'll need to find the library on your Mac. By default it should be in your Pictures folder. If you moved it or stored it elsewhere, perform a search for "photos library" on your Mac.

The girl I spoke to at apple asked me to hold my finger on the options button while I selected photos icon. The box that came up showed no files saved there. Now when I do it I see the correct files. My photos were ok a couple of weeks ago so not sure if this is anything to do with an update. May be as well phoning apple support. Good Luck!