So I've abandoned trying to get the old backup working on my iMac using the desktop app, I deleted everything that was previously there and started again.
I've left the upload running for 3 days and now have 33,000 of my 39,000 photos and videos uploaded and anything I add to my MacOS Photos app is also loading correctly.
However, my only remaining issue is that there are around 6,000 photos flagged as "Not found". This is very strange as I can find them in my Photos app and there's nothing specific or common about the ones being flagged.
As a Prime customer I have unlimited photo storage and I am not exceeding my Paid-for video quota .
This "Not Found" error will mean that the process/app that is copying your photos to the remote drive/storage is unable to locate the original data on your local storage.
Are you able to locate this missing data on your local storage in a file manager?
If you are able to locate the missing, what happens when you try to upload some of it.
Is there something different about the 6k failed photos? Are they older or a different format? or held on a separate local storage location? or owned by another user? or have different file storage permissions?
Also, can you explain how you are choosing to upload? i.e.) by drag&drop or with an app selecting a folder?
What local OS and application are you using to manage your photos locally.
Yes Peter. On the Mac is a folder called "Photos Library.photoslibrary". In Mac terms this is a"package" which is an application based folder that contains a number of sub-folders. Within this specific Photos folder is a subfolder called "Masters" which is where the actual jpg, mov, avi etc etc files sit.
I use the MacOS desktop app to run the backup and was only able to specify a folder (called "Pictures") which contained the package folder name (as opposed to just the "Masters" folder).
I have just re-run the whole backup again and still have all these "Not found" photos ranging in date from 2006 to 2019 and which vary in file type, so I can see no common aspect to all of these files.