Can't sync my Photos with finder photos from my SSD

Syncing Photos library via USB has been plagued with errors for years but lately it has been a little better.

MacOS Extended (case insensitive, journaled, GUID) is the same as HFS+ and should be used with HDD, APFS is OK especially on a SSD. Also make sure that when you Finder > Get Info of the external drive it has "Ignore ownership on this volume" at the bottom Sharing & Permissions.

Do NOT use any 3rd party virus apps or "cleaners" because they produce obscure errors and are not needed. Sometimes a clean install is needed to fix the damage they have done.

I have done this if the sync repeatedly fails or is incomplete. Doing this allows to start on a clean slate sync:

0. On the Mac quit Photos and backup the Photos library (just in case because messing inside Photos library is generally not recommended because it might corrupt it).

1. Empty the old iOS/iPadOS Photos library: Create an empty dummy folder to the Mac's Desktop. Connect iPhone/iPad via USB to the Mac. Open your home folder and choose your iPhone/iPad in the folder's sidebar, and there choose Photos tab > Sync photos to your device from: Choose folder... > choose the empty folder you just made > Apply. Wait for the sync to finish. In iPhone/iPad check that all previously synced images are deleted. If not, re-apply the sync (if there are numerous old images, deleting them might time out before all images are deleted).

2. On the Mac in your ~/Pictures folder (or wherever the Photos library is stored), right click or control-click the "Photos Library.photoslibrary", choose "Show Package Contents" and delete the "iPod Photo Cache" folder (it holds a database of previous syncs and might have been corrupted. It is re-created in the next step). Empty trash and restart the computer.

3. On the Mac open Photos.app and make sure the Photos library is set as "System Library" in Photos.app settings (you might leave Photos.app open during the sync). Connect iPhone/iPad via USB. In the Finder's Photos tab make sure "Photos" sync is ON and select all or selected albums. Hit sync a number of times until all photos are visible in iPhone/Pad Photos (might take a while with a large library).

Weird. Maybe there is some rogue image or movie that blocks the sync? But that might be impossible pinpoint if there is no identifying error message. Or maybe the fault is at the iPad side? If all else fails, I'd reset the Mac and the iPad to factory settings and restore them from backups.

Have you tried if rebuilding the Photos database helps?

How to use the Photos Repair Library tool on your Mac - Apple Support

Does it work if you crate a new smallish dummy Photos library with plain vanilla images straight from an iPhone/iPad, and try to sync that?

If that works, maybe you could "Export unmodified originals" from Photos, create a new library and import those files back to it (if you have done any metadata or pixels edits inside Photos, you might want to use a workflow that preserves those edits).

Any ideas?

Remove all 3rd party virus apps (Avast, AVG, Bitdefender, Intego, MacAfee, Norton, Kaspersky, ESET NOD32, Trusteer etc) and 3rd party "cleaning", "optimizing", "speed-up" apps (CleanMyMac, MacKeeper etc). They produce obscure errors like this and are not needed.

An EtreCheck report might provide some clues (enable full disk access for it):

Using EtreCheck to Troubleshoot Potential… - Apple Community

How to use the Add Text Feature When Post… - Apple Community

I am out of ideas. Hopefully some other user will chime in. ...what Mac, iPad, macOS and iPadOS are you using? ...have you tried to reset SMC and PRAM? ...haver you tried another USB cable? ...or to sync in safe mode? ...check the disk with Disk Utility's First Aid (from the bottom to the top)?

An EtreCheck report might provide some clues:

Using EtreCheck to Troubleshoot Potential… - Apple Community

How to use the Add Text Feature When Post… - Apple Community

• No, I don't edit photos in the Photos app. So no worries there.

That might make it slightly easier because you do not have to think if you want to preserve metadata or pixel data in each item.

I was going to suggest using "Export Unmodified Originals" from each album to a Finder folder, and then importing them back to a new Photos album (I always import files to the desired album). But with 1400 albums that might produce some RSI (repetitive strain injury) to the mouse fingers and wrist although maybe Automator.app or some script could help with that. Maybe you could test that in a smaller scale and see if the iPad then accepts the sync?

There are 3rd party apps like PowerPhotos that can manage two Photos libraries but I am not familiar with them. Maybe they could help you to copy the old and paste to a brand new Photos library that fixes the underlying issues with the old one? ...unless the possible old rogue files are carried along also with that approach... I let other users chime in with that idea.

jbauer wrote:

It's my photo library. My huge one. I can't start from scratch. Is there any way to export and re-import without losing all of the years of work that I've put into this thing? I've already tried a full photo library rebuild, and that didn't fix it. So, it must be somehow corrupted!

What work you do not want to lose? Original images (original image quality might slightly but usually unnoticeable suffer when editing pixel data), pixel edits (cropping, brightness tweaks etc), metadata edits (added and edited dates, locations, descriptions, keywords, titles), albums?