A occurs when a non-existent or empty page looks like an error page but technically returns status code instead of sending a real 404.

Example: the URL /alte-seite shows the text "This page was not found" but responds with status 200. Search engines may interpret such a page as a valid page.

Common causes are:

  • redirecting all errors to the homepage,
  • error pages that send status 200,
  • empty product pages or internal search pages with no results,
  • very with hardly any content.

The fix: genuine error pages should send (or 410 for permanent removal). A 404 page may be designed and helpful, but must technically remain a real 404. Irrelevant to the homepage should be avoided.