Two of my projects now have received this message and will not open. When I do try to open the projects I just get the window that says "cannot open project, this is not a valid Photoshop Touch project." I've tried sharing the projects to my google Drive but that didn't work and I've tried duplicating the projects but the duplicates had the same problem. Hopefully the project it's still salvageable, do please let me know, thank you.
This has happened to other users before. A bad write might have caused it.
Unfortunately, there isn't too much that can be done other than to make sure you backup your documents/projects frequently. (Make it the first thing you do when you know you want a particular project indefinitely.)