We call it a soft error when a website returns a
200 OK HTTP status code (announcing a successful operation) even though the content of the delivered page shows signs that there is something wrong with the link.
A typical example is a page that shows “Page not found” in the browser, clearly indicating a
404 Not Found error, but the server still sends
200 OK in the response header. This is usually the result of a misconfiguration or programming error.
Sometimes it’s also intentional: When a domain expires and gets snatched up by someone else, the new owner often points it to a parking page filled with ads to generate revenue. In order to avoid being detected and lose existing backlinks and search engine traffic, the server it set up to always respond with a success status code, no matter which path is requested.
Listed below are the different kinds of soft errors our crawler identifies.