In preflight Verifier:
Free Objects
text23
Object is not on a page Background
Empty Text Frame Background
These objects and pages does not exist!
Where can I find the way to correct this error?
If they are not there, Scribus would not give the error message.
It is an empty text frame that is somewhere outside a page, the Outline view is probably the best way to find it and delete it.
I think you can maybe even click the error and find the object. Yes, I just tried, I created a new document, made a text frame outside the text page and when I click the error in the preflight verifier I am brought to the empty frame.
You just need to zoom out enough to see it off the page.