For close to a year I've had this issue, every few months I get frustrated and try to research it with no luck, and have never been able to find a solution.
Since around the time I updated my mac to Catalina, I haven't been able to save a PSD a second time once I've saved it – meaning, if I save, then go back and make adjustments and hit save, it says "cannot save due to program error" and I then have to save it with a slightly different file name.
Photoshop doesn't give me this message when I go to save over a jpeg or other file type, but when you go into the finder it hasn't replaced that file (even though I click the replace button), it just makes a new file and adds "copy" on the end of the file name. In Illustrator this also causes a lot of issues when trying to relink files. If I've updated a file and managed to save over it with the same file name or rename it with the same name, it won't allow me relink the file.
I've removed and reinstalled Adobe Creative Cloud and its applications. I've reinstalled Catalina. I've had a feeling this may be related to google drive so I removed and reinstalled that. Nothing has helped.
Has anyone else had an experience like this? This is just slowing my process down a good amount, and has created a lot of excess files and created more work managing and deleting those old one-off files.