Project Save error Cubase 11 elements

Hello there. Only this week, when I’ve gone to open a project/ song I’ve been working on, I get a warning dialogue saying it was created in Cubase 1.x and my version cannot open it. It’s really messed me up as obviously I’ve worked on the songs and lost the latest changes. Please help. Thanks in advance

This means the project file is corrupted, I’m afraid.

You’ll have to open one of your backups, assuming you backup your files.