I get this "An unexpected problem occurred while opening the file. Try using a backup copy" message when I try to open an MS Project File.
But I have not backup copy. The file was created in the same version I run and I could open the file with no trouble before. Does anyone know why this message is occurrs and how to fix Project?

Universal rule step #1. Try rebooting your machine... (works often enough that's why it's a step #1). See if that works first. Maybe you will get lucky.

Unfortunately without success

Was worth a try... need to wait for some more answers now... I don't use that particular program.

I want to say thank you for taking the time to share how to go about fixing this.