Photo app not working after migration to new iMac

cmcglath wrote: I have all my photos on an external drive.

How is this external drive formatted? To get full functionality (and to avoid damaging the Photos Library) an external drive must be formatted in either APFS format or Mac OS Extended (Journaled) format. Additionally, the drive can not have had Time Machine on it since it was formatted.

Move your Photos library to save space on your Mac - Apple Support

Also, make sure that the “Ignore ownership on this volume” checkbox is selected in the command-i info window for the drive.

When you say "all my photos," do you mean in a Photos Library, or do you mean in Finder folders? or what?

How are you trying to create the Library? If you close Photos and then option-click on the Photos icon, you are given a list of Libraries that Photos can find, and you're given the option of creating a new library. Is this what you are doing?

How is this external drive connected to your Mac? It needs a wired connection - it must not be accessed remotely over your local network.

How far do you get, when you try to make the external library your System Photos Library?

• Can you open the new library in Photos by double clicking it?
• Can you access the Photos > Settings > General?
• What is the state of the button "Use as System Photos Library"? Is it dimmed or not?

If the "use as System Photos Library" button is dimmed, it can mean two things - either the library is already your system Photos Library, or it is not compatible or damaged or on a drive, that is not compatible with Photos.

To see, which library is currently your System Photos Library,

• quit Photos, if it is running.
• Then hold down the options key ⌥ and launch Photos again.
• Release ⌥ when the dialog to select a library appears.
• This dialog will show the lst of available libraries, and the current system library is tagged as system library.

When you say you are "unable" to designate a system photo library, but you have not said what happens when you try. Do you get an error message/sound or a crash, or does the "Use as System Photo Library" button just fail to go dim?

Also, when you create the photo library, are you creating it on your internal or external drive?

Hey -- it's been awhile, and all of us must have missed your last reply. (Maybe it's the weather?) Anyway, how's it going? Did you get Photos to work for you? Your settings should look like this (depending a bit on the version):

The "Use as System Photo Library" is grayed out, because it is already the System Library, so it can't be selected.

Let us know if you're up and working...

[correction: I meant if your photoslibrary is up and working, not you, really.]

Can you explain what you want to correct about the setup of your photos library?

And what you have and what you want and how they differ?