Cubase Pro 14 - Corrupted saved files

Hello.

I am working with an old Nuendo 4 project, and when I save I get this message:

The project will be saved as (project name) because of program instability after a crash.

Saving the project may cause corrupted files.

The original file will not be affected.

Please restart the program after this action!

How do I fix it? It always creates a new file after saving.