Photos library on external drive not opening

Hello,

I am in the process of configuring my new Mac Studio M4 Max. Since the new internal HD is only 512 GB, I want to keep my iTunes Music library and Photos library on an external drive.

I have copied these libraries from my Time Machine back up drive to a new SanDisk PRO-G40 2TB NVMe USB-C Portable External SSD connected via thunderbolt.

When I launch my photos app using the option button and navigate to the Photos library on the external drive I get the error: "the library could not be opened".

The external drive is formatted APFS GUID Partition map. I also unchecked "Ignore ownership on this volume"

Mac Studio (M4 Max, 2025)

Posted on Nov 13, 2025 7:22 PM

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léonie

Level 10

200,495 points

Posted on Nov 14, 2025 3:01 AM

And the external drive needs to be compatible with Photos for Mac. prepare the external drive exactly as described here: Move your Photos library to save space on your Mac - Apple Support

The essential points are:

The file system format needs to be either MacOS Extended (Journaled) or APFS
The external drive must not have been used for Time Machine backups or have any system software or backup software installed
The drive needs to be mounted locally with a wired connection, not over the local network.

Your new drive seems to be formatted correctly - the only thing you should also check, is if the formatting is case-sensitive. If yes, that could be causing problems. Make sure, the format is not case-sensitive, or you may encounter problems with videos.

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16 replies

Nov 14, 2025 12:15 PM in response to léonie

léonie wrote: … then use the commend "Restore to ..." from the contextual menu and save the restored version to your other external drive.

That doesn't actually work, at least here and with OS15. You get the the tantalizing "Restore to…," but then you don't get actual choices-- just the usual "keep, both replace." I did try to drag a Library from the "Time Tunnel?" to another location, and it always ended up in Downloads. Since I was just messing around with a small Library, I'm not sure if the copy was really from a Time Machine backup or just a current copy. … Actually, I now get a "no-can-do" icon when I try that.

Photos library on external drive not opening