the same thing just happened to me as well;
was working on a project and the files in the temp folder were erased, there was no error at the time, everything saved correctly and exited, when i tried opening the file again the above message appears;
and i did have backups, actually in multiple locations, they are all giving the same error;
I restored all the erased files from the recycle bin, but still getting an error opening the project; in fact the specific location within the appdata/local/temp folder keeps changing;
why would this error affect the backups as well?
sounds like a bug to me, if not then there's a problem with how the project details are being saved
will continue to look for work arounds, would appreciate any help that anyone else has been able to come up with