Google has updated the text they use to communicate to a searcher when the search result snippet has no information. It use to say "A description for this result is not available because of this site's robots.txt – learn more."
Now it reads "No information is available for this page. Learn why." The learn why link goes over here which explains to both the website visitor and site owner why the page is missing the snippet. The site owner is given more details on what they can do to change this outcome.
Here is the new message:
Here is the old message:
This was first spotted by @maxjpeters.
Forum discussion at Twitter.