cannot "Save as" with SBP 6.0

I’m trying to “save as” an old project with SBP 6.0 but it seems not working. It says "the save as opertion cannot be completed. Verify the file permission in your project , as well as in the destination directory then try to save again. It just doesn’t work.
How can I solve this?

Did you try the suggestions mentioned in the error message:
See that the folder path it available and that you have permission
to write to this location. Avoid having spaces, accented letters or
special symbols in any of the folder names of the folder path
you are saving to.

Alternately you can copy/paste the project folder (while the project
is closed).

Another option is to copy the panels into the library - making a
template and then making a new project and loading that template
into it.