pshill84 wrote:
No, the bug is that Photos can not locate the file, export the photo, or share it. Photos responds with a message that the file can not be found. "The operation couldn’t be completed. (PHResourceDownloadRequestErrorDomain error 0.)"
The only viewable image is actually the thumbnail, which of course loses resolution significantly when expanded.
However, if you revert to the original, the file will be restored, with none of the edits intact. It is then exportable and shareable.
Not being able to edit further would be an inconvenience. Not being able to view the full resolution photo or export and share the photo at all is a bug.
I have only been commenting on the fact, that the "revert to original" is necessary and the way Photos is working with photos that have been edited in iPhoto. This inconvenience is intentional by design and is the way how the migration from iPhoto is working, documented by Apple.
It should not happen for photos that have been edited in Photos for Mac, with or without third-party editors. It might be a bug in Photos, but is more likely a bug or an incompatibility of certain third-party editors, that need updating to be fully compatible with Photos on Catalina.
It could also be the result of a damaged Photos Library, if the library is on an incompatible volume with an incompatible file system format (for example a case-sensitive volume or an encrypted volume, a NAS), or the library has been damaged by aggressive cleaning applications when removing duplicates.
For a short time I had seen this error message, when I had edited photos on my iPhone with iOS 13. I had to revert the iPhone photos to the original before I could edit them in Photos 5 on Catalina. This has been very surprising, because Photos iOS edits used to be compatible with Photos for Mac.