Where to find Photos Error Codes for diagnostics (5600) Photos was unable to open the library “Photos Library”. (5600)

Did you just upgrade to macOS 14?

macOS 14.1 and later are no longer even trying to open a Photos Library if it is in an unsupported location. Matti already pointed out the file system format. Check, if your external SSD has exactly been prepared as described here: Move your Photos library to save space on your Mac - Apple Support

In addition to the file system format, the external drive needs a wired connection, not a network connection. And it must not have any backup software installed or be used for Time Machine backups.

Test, if you can enable the ignore ownership flag on the volume. If it is not possible, you cannot use the external drive.

To check, if the drive is suitable at all, try to create a new, empty Photos Library on the drive. Can Photos work with the new library?

I found a reference to error -5600 in this list: https://www.osstatus.com/search/results?platform=all&framework=all&search=

CarbonCore MacErrors.h errInvalidWindowPtr -5600

CarbonCore MacErrors.h errInvalidWindowRef -5600

That is program error, that not should happen. It might be caused by having incompatible third-party software installed. You may to try, if you are getting the same error message, when running your Mac in Safe Mode. This will clear some caches and disable third-party system extensions.

yamoinca, I don't have an answer to your question about where to find error codes, other than to say I asked Apple phone support (in Australia) if they had a record of this error code, and they said no. I agree with you, if Apple made this information publicly available (or at very least provided it to their own support people!), that would be very helpful.

What I can share is what worked for me, in the hope that it will help you or someone else encountering the same bug. I'm convinced it is a bug in Photos, and not a problem with the drive, because I have a massive Final Cut Pro library on the same drive, and it never had a problem.

Here's the procedure that I went through with Apple support:

1. Create a new user account. (She said to give it admin privileges, but I now realise I forgot to do this, and just left it as a standard account.)
2. With the external drive still connected, log out from your usual account and log in to the new account.
3. Open the Photos app with the Option key held down and select the Photos library from your external drive.
4. With any luck, the Photos app will now update the library. (This took about 5 minutes for me.) Once that is complete, verify that your library has opened successfully.
5. Quit out of Photos and log out of the user account.
6. Log back in to your own account and launch Photos again. (This time it said it was updating the library again, with it immediately at 93% complete. Then it briefly said 'Restoring' (from memory), then the library successfully opened.)

As a final test, I quit Photos, ejected the SSD, plugged it in again and restarted Photos. The library loaded successfully again.

Hope that helps someone!!

external SSD

Make sure the external SSD is formatted as APFS (or MacOS Extended for HDD). Non-Mac formats like exFAT, FAT, NTFS, and also network shares or Time Machine volumes are not supported and might very well corrupt the library. Some macOS versions reinforced this but some do not (I wish there was a clearly worded alert to the user about this).

@Matti Haveri and @léonie: I can't speak for the OP, but my external SSD drive (and it's the same for other people I've seen post about this issue) ticks all the boxes: wired connection, APFS formatted, not used for Time Machine, 'Ignore ownership' is ticked, etc. It's an expensive OWC Thunderbolt 3 drive, and I've never had any problems with it.

When I spoke to the Apple support person, she suggested that the Mac was having trouble communicating with the drive, but that's clearly not the case as it's perfectly usable in the Finder, and Final Cut Pro has no trouble accessing libraries from it either. This appears to be a bug that is limited to the Photos app.

@léonie: It happened to me after upgrading to macOS 13 Ventura. You haven't raised my hopes for things to get any better with macOS 14! 🫤

Yes, running in Safe Mode could be another thing to try. As mentioned, it also worked from a new Mac account. But it could also be because the drive was plugged in when first logging in to the account. That seems to be a temporary fix for this problem (reported by others too).

UPDATE: My fix was short lived. I plugged the drive in again today, and hit the same error again. Logging out and in again with the drive plugged in got it working again, so that seems to be a reliable workaround. But the permanent fix I had hoped for remains elusive.

Kalsta,

It looks like the account is the problem, doesn't it? Your account may be automatically running "cleaning" type software, or something else that looks benign but isn't. You should look at your login items to see if any have been added that you didn't plan on. I've pretty much eliminated all of them.

Safe Mode shuts many of those things down, so if all seems good in Safe Mode, that would be telling. Actually, just running in Safe Mode sometimes fixes things. In any case, you should look closely for problems with this account.

Hold it-- I just re-read léonie's post, and I see she said much the same. Must be a good idea....