I was working today on a new created project on Cubase 8.5.20 on a mac OS X 10.11.6.
The project had an automatically created folder.
I didn’t save during the work on the project, and typically Cubase crashed.
I started Cubase again, clicked on “open other” in the New project window and went to the folder of my latest created project. When I tried to start the latest backup file I had the error message “Invalid project file”.
Though when I tried to open the older backup file Cubase didn’t encounter difficulties.