Apple Photos says referenced files are "missing" after moving external drive to another machine
Mojave 10.14.6
Photos 4.0
I have my Photos Library on an external drive, and on the same drive are the photo files in folders as referenced files. All has been good.
I physically disconnected the external drive and connected it to a different Mac, running same version of Mojave and Photos. The referenced files all come up "missing".
Drive names were not changed. File paths were not changed.
Repairing the Library did not correct the problem.
The external drive is formatted as Mac OS Extended Journaled.
Ignore ownership on this volume is checked.
I have run first aid on the drive and it is fine.
In Photos, when I use the option to find the missing file, it always takes me to the correct folder for the missing image, I only have to hit return to accept it, and it works, the file is no longer missing. However, with 94,000 files, it would take a tremendous effort to fix them all.
As a test, I made a new Photos database on a different (similarly prepared) external drive and handful of images. As before, when I physically moved the drive to the other Mac, the same problem occurred. All of the files were "missing". If I move the disk back to the first computer without finding/fixing the missing files, it is fine (photos are not "missing").
To further the experiment, on the second computer, I reimported the handful of test photos (from their same referenced locations). They were not recognized as duplicates on import, even though they are the exact same files in the exact same locations. They imported successfully, and there are two sets of the same images, from exact same files on disk in Photos. The newly imported files are not "missing" according to Photos, but the files imported on the first computer continue to be "missing". So, I moved the external drive back to the first computer, and, the files imported first, from that computer, are no longer "missing", and the files imported on the second computer are "missing". In other words, the files are not "missing" as long as the external drive is connected do the computer where they were originally imported.
I spent an hour on the phone with Apple Support and they were not able to resolve the problem, though they tried. This was before I replicated the problem with a fresh library, for what it's worth.
As far as I can tell, the drive and the files are fine, but for some reason the Photos app cannot properly find the files when I move the external drive to a different machine.
I have also tried moving the external drive to a third computer running Big Sur and Photos 6.0. Same problem. One difference is that Photos 6.0 on Big Sur is revamped, and so it does an migration/update process on the Library. Outcome is the same.
I have backups of the files and the library. No worries in that regard.
My goal, ultimately, is to successfully migrate to Big Sur and Photos 6.0.
I have not attempted migration through Time Machine or Migration Assistant. I am not optimistic about those routes based on what I've read online. I do not have room on the system disks of any of my machines to put the photos there. I suppose I should test these options.
I have opened the Photos.db file and investigated RKVolume and RKMaster tables. Everything seems in order, but I could easily be missing something. I've compared before and after moving to different computer.
I have explored the possibility that XATTRS are playing a role. It seems they are not, but again, I could be missing something.
The fact I can replicate the problem with a fresh Photos library and as few as 1 file suggests to me that my Library is not corrupt. And the fact I have replicated it on a different external disk suggests to me that the disk is fine. I've tested with a combination older and brand new photos with the same results.
I would rather not consolidate my files within the Library, but I might resort to that, if tests show that it resolves the problem.
I'm tempted to say there is a serious bug in Photos. I know others have had similar sorts of issues, though more often having to do with renaming a volume. I keep hoping that I'll find some little trick that makes it all work out. My gut tells me, at this point, that the problem is not so much with Photos as it is with how the Mac manages external drives.
Every several years I consider moving to something else. I tried and was happy with Aperture. From there I went to LightRoom. I didn't like it. I came back to Photos. It is hugely problematic that there is no way to export everything and reimport it without loss of effort invested in organizing and editing. I am considering moving to file system approach using GraphicConverter and ACDSee PhotoStudio for Mac, but this would be a major change.
Anyone else having the same problem?
If anyone has any ideas about what is causing the files to be "missing" in the way they are, I'd appreciate hearing them. Thanks.
Mac mini 2018 or later