VC4001: Link to a page that doesn't exist
A link to a page on this site (/about) that doesn't exist, so visitors get a not-found page. Links passed to a block as a parameter it uses as an href are checked too.
How to fix
Point it at an existing page (the quick fix offers the closest), or create the page. Paths with a file extension (/favicon.ico) and system paths aren't checked.