I am getting the above message every time I try to save a file twice. So, the first time I save not a problem at all. If I go back to that image and re-edit it I get the error message. The only way I'm able to save it is by putting it in a completely different folder. This has just startted happening. I'm using Catalina 10.15.7
I have not had this issue before and it's happening with lots of different images fron different folders so I know it's not an error with the file itself.
Hope there's a fix!