Cannot Open File - Using Older File Format?

Hi! I reformatted my computer and reinstalled scrivener but when I tried to launch project file it said that I was using an older file format. The file format is Scrivener 3, and it is no different from what I have installed before. It will not allow me to update the file for use - does anyone have any suggestions?

It asked your permission to upgrade the project and you said no?

Where was your data while you were reformatting the computer? And what exact error message did you see?