Very slow first iPhone and iPad photo sync over usb-a with Catalina

It helps me not to go mad, to find some people here from the slow sync discussion 6 months ago!

Situation is for me that if I only sync images in photo app it works.....but this is no way for me....I have to sync fotos from normal MacOS diretories....and have to wait for hours....

I have been having the same issue too. Started last February/March and only solution that was to get a copy of iTunes 12.9.2.5 and use that. Everything went back to normal..

Now that we are on Catalina and iTunes won't even open, a new fix is required. Only thing I've found so far is to delete the iPod photo cache every single time I press sync. It takes well under an hour to re-sync c10,000 photos/500 videos to my phone but if the cache isn't deleted every single time it just syncs for hours and hours to the point where I now only do it overnight.

I have had the same problem as all of you since a random iTunes update months ago - I had to stop syncing my phone because the 16,000 photo s would take hours; Activity Monitor checking iTunes Open Files and Ports would show it accessing the photo directories very slowly. Upgrading to Catalina didn't help at all; the only difference is now the directories show in AMPDevicesAgent, which is 100% CPU during the entire sync.

On the very first sync from Catalina to my iPhone, Finder was 100% CPU and unresponsive except for the ex-iTunes-like labels on top (General, Music, Movies, etc.), and the cooling fans were running fast. After I force quit Finder after the first sync, any sync after that makes AMPDevicesAgent use 100% instead, but the calling fans don't need to spin up. (The first sync didn't copy everything and the copied images were not in time order; after the 2nd sync they all existed and in the same order.)

A worse issue is syncing to my iPad Pro 11". On that, it replaces about 30% of the photos with a solid blank image, and used space/free space shows it not using as much space as before. A second sync made no changes, but took even longer (I think 9 hours). I changed from All folders to Selected folders and just selected 1 to get rid of the rest (I'm syncing from a data folder that has about 50 folders inside it, so those 50 are what show in the Folders section), then went back to All; after an overnight sync, it was the same as before (and it looks like the same images that were blank before are blank now, but they're fine on my iPhone 11 Pro).

I think I've tried deleting the iPod Photo Cache in that data folder before (with iTunes on Mojave) and I din't remember it making any difference; but in iTunes it would show Copying 1 of 16,000 and show progress; Finder shows nothing (once it showed a completion percentage dial next to the iPad, but usually it just shows the sync spinning circle).

It’s a bit hit and miss at the moment.

but deleting the cache will work. You just need to make Finder think the phone wants the photos synced.

I normally have to toggle the “Sync Photos” tick box a bit. Sometimes the button then says apply and will then sync, sometimes the button changes to sync but doesn’t do anything. It’s a total mess but if you get the sync button working at least you know it will work quicker if the cache has already been deleted.

Yeah it’s crazy that you can rebuild an entire cache an re sync 10000 photos in less time than you can add one photo and sync it. I wonder if Apple are making it unreliable deliberately to try and get more people to get frustrated and end up using the iCloud Photo Library???

I would really appreciate if someone could post here where I can find the cache. If I select to sync from Folders on my HardDrive (instead of the Photos App) I know that a cache File is created (something starting with pod) in the Folder which I sync. But if I select the Photo App to sync from I do not know where to find it.

I tried that, but when I let it rebuild, a lot of the older photos (taken with the original iPhone) get their thumbnails created as just a black box. I'm now forced to sync 1 additional folder at a time, and with each one added, the sync time gets slower and slower. Worse, this is all happening syncing to an iPad, so when I eventually sync my iPhone, I don't know if the cache will need to be rebuilt for the different screen size.

How did you rebuild and sync as two separate steps? (As for mine, after about 9k photos in 25 folders done mostly 1 folder at a time, the next one (first in the list with over 1000 photos) had black in half of the images. I gave up, removed all photos from the iPad, and after I reboot, I'm deleting my cache and restoring from Time Machine from before this mess started (because at least the sync last week to my phone worked, which is more important since it's the only device i HAVE to sync for music). I'd restore Mojave, but I just upgraded Reminders so I can't go back.

...and it looks like iPod Photo Cache is excluded from Time Machine backups, so I guess I'm not looking at my photos on my large iPad anymore, just my iPhone. I'd say I'll wait for Apple to fix it, but it's been slow for over half a year, and I seem to be the only one reporting corrupted thumbnails (yes, I submitted feedback).

I am experiencing the same issue as everyone else here on Catalina and iOS 13.1.2 - so far I have had repeatable success in syncing most photos by removing the "iPod Photo Cache" folder. However, I have also noticed that some of my photos are missing from some albums and I haven't been able to identify any patterns for those photos missing from different albums. While I am trying other experiments to see if I can get these missing photos to also sync, has anyone had similar experiences?

When I look at it, it looks like a database (it's a list of the full path to all the processed images plus binary data); yours looks like the output of some script that ran (which might be useful to know what it was). As for the bash to zsh update notice, that's something standard any time you open Terminal in Catalina, unless you change the default shell or tell the Mac to stop showing that message. (I haven't updated yet, partly because I've been busy with the photo cache issues.)

It is a bug in Catalina, so 13.1.3. does not result in any solution.

The really sad news: even the first Catalina update does not promise any help, and indeed does not result in any solution. So please continue to inform Apple about your issues. Not only here, call them, use contact forum,...